Option (b) is correct.

The fallacy of Viruddha (also known as the fallacy of contradiction) in Nyaya occurs when two statements contradict each other. Option (b) involves the fallacy of Viruddha because it contradicts the widely accepted belief that sound is not eternal. The argument "Sound is eternal because it is produced" is based on the assumption that anything that is produced is eternal, which is not true in the case of sound.

Option (a) is a valid syllogism because it follows the logical form "The hill has smoke because it has fire. This hill has fire. Therefore, this hill has smoke." This syllogism has a clear middle term (fire) and both premises are true, leading to a valid conclusion.

Option (c) is an example of the fallacy of Sadharana, which occurs when the middle term in a syllogism is too broad. In this case, the argument is "The hill has fire because it is knowable. Therefore, this hill has fire." The middle term "knowable" is too broad and includes things that may not have fire, leading to an invalid conclusion.

Option (d) is an example of the fallacy of argument from eternity, which occurs when something is assumed to be eternal without sufficient evidence or reasoning. The argument is "Sound is eternal because it is audible." This assumes that because sound can be heard, it must be eternal, which is not a valid argument. There are many things that can be heard that are not eternal.

विकल्प (b) सही है।

“ध्वनि शाश्वत है क्यूंकि यह उत्पन्न होती है”।

उपर्युक्त वाक्य में भारतीय न्याय तर्कशास्त्र - मत के अनुसार विरूद्ध तर्कदोष निहित है। इस वाक्य में मध्य पद अपने आप मौलिक प्रज्ञिप्त को असत्य सिद्ध करता है और इस लिए यह कथन व्याघाति है।