The correct answer is option 'C', which states that a decoder converts n inputs to 2^n outputs. Let's understand why this answer is correct by breaking it down into the following points:

1. Definition of a decoder:
- A decoder is a digital circuit that takes a binary input of n bits and produces 2^n possible output combinations.
- It is the opposite of an encoder, which converts 2^n inputs into n outputs.

2. Understanding the input:
- In the given question, it is stated that a decoder converts n inputs.
- Here, 'n' represents the number of input lines or bits that the decoder takes as input.

3. Understanding the output:
- The question asks about the number of outputs produced by the decoder.
- The answer option 'C' states that the decoder produces 2^n outputs.
- Here, '2^n' represents the total number of possible output combinations that can be generated from 'n' input lines.

4. Explanation:
- To understand why the decoder produces 2^n outputs, let's consider an example. Suppose we have a 2-input decoder with input lines A and B.
- The decoder will have 2^2 = 4 possible combinations of inputs: (00, 01, 10, 11).
- For each input combination, the decoder will produce a unique output combination.
- In this case, the decoder will have 4 outputs: Y0, Y1, Y2, and Y3.
- So, for 'n' input lines, the decoder will have 2^n possible combinations and hence, 2^n outputs.

5. Conclusion:
- Based on the above explanation, it is clear that a decoder converts 'n' inputs to 2^n outputs.
- Therefore, option 'C' is the correct answer to the given question.