Option (b) is correct.

Sewage refers to the wastewater generated from households, businesses, and industries that contains various organic and inorganic substances. Among the organic substances present in sewage are oxygen-demanding wastes, also known as biodegradable or organic pollutants. Here's an explanation of sewage and oxygen-demanding waste:

1. Sewage: Sewage is the collective term for wastewater that includes water from toilets, sinks, showers, and industrial processes. It may contain a variety of substances such as human waste, soaps, detergents, food particles, oils, chemicals, and other organic and inorganic materials. Sewage can carry disease-causing microorganisms, nutrients like nitrogen and phosphorus, and other pollutants.
2. Organic Pollutants: Organic pollutants in sewage are primarily composed of biodegradable or carbon-based materials. These materials are derived from various sources, including human waste, food remnants, and other organic matter that enters the sewage system. Examples of organic pollutants in sewage include proteins, carbohydrates, fats, oils, and detergents.
3. Oxygen-Demanding Waste: Oxygen-demanding waste refers to the organic pollutants present in sewage that have the potential to consume dissolved oxygen in water during the process of decomposition. When sewage is discharged into water bodies, such as rivers or lakes, bacteria and other microorganisms break down the organic pollutants present in the sewage as they consume oxygen.

During the decomposition process, bacteria utilize oxygen to break down organic matter and release carbon dioxide (CO2) and other by products. The consumption of dissolved oxygen in the water by these microorganisms can create an oxygen-deficient environment, leading to a decrease in oxygen levels in the water. This reduction in oxygen can negatively impact aquatic organisms, including fish and other aquatic life, as they rely on dissolved oxygen to survive.

Excessive oxygen-demanding waste in sewage can cause a condition called hypoxia or "dead zones" in water bodies, where oxygen levels are extremely low, leading to the death of marine life and the disruption of ecosystems.

To mitigate the negative effects of oxygen-demanding waste in sewage, wastewater treatment processes are employed. These processes, such as primary, secondary, and tertiary treatment, aim to remove organic pollutants and other contaminants from sewage before it is discharged into the environment. The treatment processes help reduce the levels of oxygen-demanding waste and other pollutants, making the treated wastewater safer for release into water bodies or for reuse in various applications.

In summary, oxygen-demanding waste refers to the organic pollutants present in sewage that have the potential to consume dissolved oxygen in water during the decomposition process. Proper treatment of sewage is essential to remove or reduce the levels of oxygen-demanding waste and prevent its harmful effects on aquatic ecosystems.

Agricultural-Plant nutrients are essential elements that are necessary for the growth and development of plants in agriculture. Plants require a range of nutrients to carry out their metabolic processes, maintain their structure, and produce high-quality crops. Here's an explanation of agricultural plant nutrients:

1. Macronutrients: Plants require macronutrients in large quantities. The primary macronutrients include:
• Nitrogen (N): Nitrogen is crucial for the synthesis of proteins, enzymes, chlorophyll, and other essential compounds in plants. It promotes leaf and stem growth.
• Phosphorus (P): Phosphorus is involved in energy transfer and storage, as well as the development of roots, flowers, and fruits.
• Potassium (K): Potassium is vital for enzyme activation, osmoregulation, and the overall growth and health of plants. It contributes to root development, disease resistance, and the transport of water and nutrients within the plant.
2. Secondary Nutrients: Plants also require secondary nutrients, which are needed in moderate quantities. The secondary nutrients include:
• Calcium (Ca): Calcium is essential for cell wall formation, root development, and proper functioning of enzymes in plants.
• Magnesium (Mg): Magnesium is a central component of chlorophyll, playing a crucial role in photosynthesis and energy production.
3. Micronutrients: Micronutrients are essential elements that plants require in small amounts. Although they are needed in trace quantities, they are still critical for plant growth and development. Some important micronutrients include:
• Iron (Fe): Iron is necessary for chlorophyll synthesis, enzyme activation, and energy transfer in plants.
• Zinc (Zn): Zinc is involved in enzyme function, protein synthesis, and hormone regulation in plants.
• Manganese (Mn): Manganese plays a role in photosynthesis, nitrogen metabolism, and enzyme activation.
• Copper (Cu): Copper is required for enzyme activity and plays a role in photosynthesis and reproductive processes.
• Boron (B): Boron is essential for cell wall formation, pollen development, and the metabolism of carbohydrates in plants.
• Molybdenum (Mo): Molybdenum is necessary for nitrogen fixation and the metabolism of nitrogen in plants.

These agricultural plant nutrients are naturally present in soil, but their availability to plants can vary. Soil fertility management practices, such as adding fertilizers, organic matter, and amendments, can help ensure an adequate supply of nutrients for plant growth. Farmers and gardeners often conduct soil tests to assess nutrient levels and make informed decisions about fertilization.

Appropriate nutrient management is essential to optimize crop productivity, prevent nutrient deficiencies or toxicities, and promote sustainable agricultural practices. By understanding the nutrient requirements of plants and maintaining balanced nutrient levels, farmers can support healthy plant growth, improve crop yields, and contribute to sustainable and efficient agricultural systems.

Land erosion refers to the process by which soil, rocks, and other materials are moved and displaced from one location to another. Sediments, in the context of land erosion, refer to the particles of soil and other materials that are eroded and transported by natural agents like water, wind, or gravity. Here's an explanation of land erosion and sediments:

1. Land Erosion: Land erosion occurs when the natural integrity of the land surface is disrupted, leading to the removal and displacement of soil, rocks, and other materials. Erosion can be caused by several factors, including:
• Water Erosion: This occurs when rainfall or flowing water dislodges and carries away soil particles. It can be further categorized into sheet erosion (uniform removal of a thin layer of soil), rill erosion (formation of small channels), and gully erosion (formation of larger, deeper channels).
• Wind Erosion: Wind erosion happens when strong winds lift and transport loose soil particles. It is common in arid and semi-arid regions with sparse vegetation.
• Gravity Erosion: This type of erosion is triggered by gravity and is commonly seen in hilly or mountainous areas. Examples include landslides, rockfalls, and slope failures.
2. Sediments: Sediments are the eroded particles of soil, rock fragments, and other materials that are carried away by erosion agents. These particles can vary in size, ranging from fine silt and clay to coarser sand, gravel, and even larger rocks. Sediments are transported by natural agents such as water, wind, or gravity, and can be deposited in other locations, including rivers, lakes, reservoirs, coastal areas, or even agricultural fields.
3. Impacts of Land Erosion and Sediments: Land erosion and the resulting sedimentation can have several negative impacts on the environment and human activities:
• Soil Degradation: Erosion removes the fertile topsoil, which is rich in nutrients and organic matter necessary for plant growth. This loss of soil can decrease agricultural productivity and degrade the land's ability to support vegetation.
• Water Quality Issues: Sediments carried by erosion can be deposited in rivers, lakes, and other water bodies. Excessive sedimentation can degrade water quality, reduce light penetration, and harm aquatic habitats. Sediments may also carry pollutants such as pesticides, fertilizers, and heavy metals, leading to water pollution.
• Infrastructure Damage: Erosion and sedimentation can damage infrastructure, including roads, bridges, and buildings, especially in areas prone to landslides, riverbank erosion, or coastal erosion.
• Habitat Loss: Erosion and sedimentation can alter or destroy natural habitats, including wetlands, rivers, and coastal areas, impacting wildlife and biodiversity.
• Increased Flooding: Sediment deposition in rivers can reduce their capacity to carry water, leading to increased flood risks during heavy rainfall events.

Preventing or minimizing land erosion and sedimentation requires implementing erosion control measures such as terracing, contour plowing, reforestation, vegetative cover, and erosion control structures. These measures help reduce the erosive forces and promote the retention of soil and sediments in their original locations, thus mitigating the negative impacts on the environment and human activities.

In summary, land erosion refers to the process of soil and material displacement, while sediments are the particles of soil and other materials eroded and transported by natural agents. Land erosion and sedimentation can have adverse effects on soil fertility, water quality, infrastructure, habitats, and flooding. Implementing erosion control measures is crucial to mitigate these impacts and promote sustainable land and water management.

Power plants are facilities that generate electricity by converting various sources of energy into electrical power. One common type of power plant is a thermal power plant, which generates electricity by using heat to produce steam that drives a turbine connected to a generator. However, thermal power plants can also contribute to a form of pollution known as thermal pollution. Here's an explanation of power plants and thermal pollution:

1. Power Plants: Power plants are large-scale facilities designed to generate electricity on a significant scale. They use different energy sources to produce the mechanical or thermal energy needed to rotate turbines, which, in turn, generate electrical power. Common energy sources used in power plants include fossil fuels (such as coal, oil, and natural gas), nuclear energy, and renewable sources like solar, wind, hydroelectric, and geothermal energy.
2. Thermal Power Plants: Thermal power plants, also known as steam power plants, rely on the combustion of fossil fuels or nuclear reactions to generate heat. The heat produced is used to generate steam by heating water, and the steam is then directed towards a turbine. The high-pressure steam causes the turbine to rotate, which drives an electrical generator to produce electricity.
3. Thermal Pollution: Thermal pollution refers to the undesirable increase in the temperature of a water body caused by human activities, particularly those associated with industrial processes like power generation. Thermal pollution occur when power plants or other industrial facilities use water from nearby water bodies, such as rivers, lakes, or oceans, for cooling purposes. The heated water is then discharged back into the water body at a higher temperature than before, which can have various negative effects:
• Decreased Oxygen Levels: Higher water temperatures can reduce the solubility of oxygen in water, leading to lower oxygen levels. This can harm aquatic organisms that rely on oxygen, potentially causing fish kills and impacting other forms of aquatic life.
• Altered Aquatic Ecosystems: Increased water temperatures can disrupt the natural balance of aquatic ecosystems. Some species may thrive in warmer waters, while others may struggle or even die off. Changes in the distribution and abundance of aquatic species can have cascading effects on the entire ecosystem.
• Increased Biological Activity: Warmer water temperatures can enhance the growth of certain organisms, such as algae, bacteria, and parasites. Excessive growth of these organisms can lead to algal blooms, harmful algal blooms, or an imbalance in the ecosystem, affecting water quality and ecosystem health.
• Disruption of Migration Patterns: Higher water temperatures can affect the migration patterns of fish and other aquatic organisms, as their movement is often influenced by temperature changes. This disruption can impact reproduction, feeding patterns, and the overall health of migratory species.
• Reduced Efficiency of Cooling Systems: Thermal pollution can also reduce the efficiency of power plant cooling systems. As the temperature of the cooling water increases, the cooling capacity of the system decreases, which can affect the plant's overall energy efficiency.

To mitigate thermal pollution, power plants can employ various cooling techniques, such as using cooling towers or cooling ponds that minimize the direct release of heated water back into water bodies. Additionally, implementing environmental regulations and adopting cleaner energy sources that produce less waste heat can help reduce the impact of thermal pollution from power plants.

In summary, power plants, including thermal power plants, generate electricity by converting energy sources into electrical power. Thermal pollution, a form of pollution associated with power plants, occurs when heated water is discharged back into water bodies, leading to increased water temperatures that can harm aquatic ecosystems, reduce oxygen levels, and disrupt aquatic species' behavior and habitats. Efforts to mitigate thermal pollution include improved cooling techniques and the use of cleaner and more efficient energy sources.

विकल्प (b) सही है।

सीवेज घरों, व्यवसायों और उद्योगों से उत्पन्न अपशिष्ट जल को संदर्भित करता है जिसमें विभिन्न कार्बनिक और अकार्बनिक पदार्थ होते हैं। सीवेज में मौजूद कार्बनिक पदार्थों में ऑक्सीजन की मांग वाले अपशिष्ट हैं, जिन्हें बायोडिग्रेडेबल या कार्बनिक प्रदूषक भी कहा जाता है। यहां सीवेज और ऑक्सीजन की मांग वाले कचरे का स्पष्टीकरण दिया गया है:

1. सीवेज: सीवेज अपशिष्ट जल के लिए सामूहिक शब्द है जिसमें शौचालय, सिंक, शॉवर और औद्योगिक प्रक्रियाओं से पानी शामिल है। इसमें मानव अपशिष्ट, साबुन, डिटर्जेंट, खाद्य कण, तेल, रसायन और अन्य कार्बनिक और अकार्बनिक सामग्री जैसे विभिन्न प्रकार के पदार्थ हो सकते हैं। सीवेज रोग पैदा करने वाले सूक्ष्मजीवों, नाइट्रोजन और फास्फोरस जैसे पोषक तत्वों और अन्य प्रदूषकों को ले जा सकता है।

2. कार्बनिक प्रदूषक: सीवेज में कार्बनिक प्रदूषक मुख्य रूप से बायोडिग्रेडेबल या कार्बन-आधारित सामग्रियों से बने होते हैं। ये सामग्री विभिन्न स्रोतों से प्राप्त होती है, जिसमें मानव अपशिष्ट, खाद्य अवशेष और अन्य कार्बनिक पदार्थ शामिल हैं जो सीवेज प्रणाली में प्रवेश करते हैं। सीवेज में कार्बनिक प्रदूषकों के उदाहरणों में प्रोटीन, कार्बोहाइड्रेट, वसा, तेल और डिटर्जेंट शामिल हैं।

3. ऑक्सीजन की मांग वाला अपशिष्ट: ऑक्सीजन की मांग वाला अपशिष्ट सीवेज में मौजूद कार्बनिक प्रदूषकों को संदर्भित करता है जो अपघटन की प्रक्रिया के दौरान पानी में घुलित ऑक्सीजन का उपभोग करने की क्षमता रखते हैं। जब सीवेज को जल निकायों, जैसे नदियों या झीलों में छोड़ दिया जाता है, तो बैक्टीरिया और अन्य सूक्ष्मजीव सीवेज में मौजूद कार्बनिक प्रदूषकों को तोड़ देते हैं क्योंकि वे ऑक्सीजन का उपभोग करते हैं।

अपघटन प्रक्रिया के दौरान, बैक्टीरिया कार्बनिक पदार्थों को तोड़ने और कार्बन डाइऑक्साइड (सीओ 2) और अन्य उत्पादों को छोड़ने के लिए ऑक्सीजन का उपयोग करते हैं। इन सूक्ष्मजीवों द्वारा पानी में घुलित ऑक्सीजन की खपत ऑक्सीजन की कमी वाला वातावरण बना सकती है, जिससे पानी में ऑक्सीजन के स्तर में कमी हो सकती है। ऑक्सीजन में यह कमी मछली और अन्य जलीय जीवन सहित जलीय जीवों को नकारात्मक रूप से प्रभावित कर सकती है, क्योंकि वे जीवित रहने के लिए घुलित ऑक्सीजन पर भरोसा करते हैं।

सीवेज में अत्यधिक ऑक्सीजन की मांग वाले कचरे से जल निकायों में हाइपोक्सिया या "मृत क्षेत्र" नामक स्थिति पैदा हो सकती है, जहां ऑक्सीजन का स्तर बेहद कम होता है, जिससे समुद्री जीवन की मृत्यु हो जाती है और पारिस्थितिक तंत्र का विघटन होता है।

सीवेज में ऑक्सीजन की मांग वाले कचरे के नकारात्मक प्रभावों को कम करने के लिए, अपशिष्ट जल उपचार प्रक्रियाओं को नियोजित किया जाता है। प्राथमिक, द्वितीयक और तृतीयक उपचार जैसी इन प्रक्रियाओं का उद्देश्य पर्यावरण में निर्वहन से पहले सीवेज से कार्बनिक प्रदूषकों और अन्य दूषित पदार्थों को हटाना है। उपचार प्रक्रियाएं ऑक्सीजन की मांग वाले अपशिष्ट और अन्य प्रदूषकों के स्तर को कम करने में मदद करती हैं, जिससे उपचारित अपशिष्ट जल निकायों में छोड़ने या विभिन्न अनुप्रयोगों में पुन: उपयोग के लिए सुरक्षित हो जाता है।

सारांश में, ऑक्सीजन की मांग वाला अपशिष्ट सीवेज में मौजूद कार्बनिक प्रदूषकों को संदर्भित करता है जो अपघटन प्रक्रिया के दौरान पानी में घुलित ऑक्सीजन का उपभोग करने की क्षमता रखते हैं। ऑक्सीजन की मांग वाले कचरे के स्तर को हटाने या कम करने और जलीय पारिस्थितिक तंत्र पर इसके हानिकारक प्रभावों को रोकने के लिए सीवेज का उचित उपचार आवश्यक है।

कृषि-पादप पोषक तत्व आवश्यक तत्व हैं जो कृषि में पौधों की वृद्धि और विकास के लिए आवश्यक हैं। पौधों को अपनी चयापचय प्रक्रियाओं को पूरा करने, उनकी संरचना को बनाए रखने और उच्च गुणवत्ता वाली फसलों का उत्पादन करने के लिए पोषक तत्वों की एक श्रृंखला की आवश्यकता होती है। यहां कृषि पौधों के पोषक तत्वों की व्याख्या दी गई है:

1. मैक्रोन्यूट्रिएंट्स: पौधों को बड़ी मात्रा में मैक्रोन्यूट्रिएंट्स की आवश्यकता होती है। प्राथमिक मैक्रोन्यूट्रिएंट्स में शामिल हैं:

• नाइट्रोजन (एन): पौधों में प्रोटीन, एंजाइम, क्लोरोफिल और अन्य आवश्यक यौगिकों के संश्लेषण के लिए नाइट्रोजन महत्वपूर्ण है। यह पत्ती और तने के विकास को बढ़ावा देता है।

• फास्फोरस (पी): फास्फोरस ऊर्जा हस्तांतरण और भंडारण में शामिल है, साथ ही जड़ों, फूलों और फलों के विकास में भी शामिल है।

• पोटेशियम (के): पोटेशियम एंजाइम, ऑस्मोरग्यूलेशन और पौधों के समग्र विकास और स्वास्थ्य के लिए महत्वपूर्ण है। यह जड़ विकास, रोग प्रतिरोध, और पौधे के भीतर पानी और पोषक तत्वों के परिवहन में योगदान देता है।

2. द्वितीयक पोषक तत्व: पौधों को द्वितीयक पोषक तत्वों की भी आवश्यकता होती है, जिनकी मध्यम मात्रा में आवश्यकता होती है। द्वितीयक पोषक तत्वों में शामिल हैं:

• कैल्शियम (सीए): कैल्शियम कोशिका भित्ति निर्माण, जड़ विकास और पौधों में एंजाइमों के उचित कार्य के लिए आवश्यक है।

• मैग्नीशियम (मिलीग्राम): मैग्नीशियम क्लोरोफिल का एक केंद्रीय घटक है, जो प्रकाश संश्लेषण और ऊर्जा उत्पादन में महत्वपूर्ण भूमिका निभाता है।

3. सूक्ष्म पोषक तत्व: सूक्ष्म पोषक तत्व आवश्यक तत्व हैं जिनकी पौधों को कम मात्रा में आवश्यकता होती है। यद्यपि उन्हें सूक्ष्म मात्रा में आवश्यक है, फिर भी वे पौधे की वृद्धि और विकास के लिए महत्वपूर्ण हैं। कुछ महत्वपूर्ण सूक्ष्म पोषक तत्वों में शामिल हैं:

• आयरन (Fe): पौधों में क्लोरोफिल संश्लेषण, एंजाइम सक्रियण और ऊर्जा हस्तांतरण के लिए आयरन आवश्यक है।

• जिंक (Zn): जिंक पौधों में एंजाइम फ़ंक्शन, प्रोटीन संश्लेषण और हार्मोन विनियमन में शामिल है।

• मैंगनीज (Mn): मैंगनीज प्रकाश