Step 1: Understanding Nyaya Inference.
Nyaya Inference is a part of the Nyaya school of Indian philosophy, which deals with logical reasoning. The elements of Nyaya inference are:
- Hetu: The reason or cause.
- Udaharana: The example or illustration.
- Upanaya: The application of the reason to the example.
Prasna, which refers to the question or inquiry, is not a part of Nyaya Inference but rather a part of the process of logical inquiry.
Step 2: Analyzing the Options.
- 1. Prasna: This is incorrect. Prasna refers to the question but is not part of the inference process in Nyaya logic.
- 2. Udaharana: This is correct. Udaharana refers to the example and is an essential element of Nyaya Inference.
- 3. Hetu: This is correct. Hetu is the reason used in the logical process of inference.
- 4. Upanaya: This is correct. Upanaya is the application of the reason to the example in the inference process.
Step 3: Conclusion.
The correct answer is 1. Prasna.
Final Answer:
\[
\boxed{\text{The correct answer is 1. Prasna.}}
\]