**0**

Here is the catch 2 answers(a and d) are 1/4, if the answer is 1/4, then because 2 out of 4 answer choices are ‘1/4’, the answer must actually be 1/2. This is a contradiction. So the answer cannot be 1/4.

If the answer is 1/2 (or 1), then because 1/2 (or 1) is 1 out of 4 answer choices, the answer must be 1/4. This is again a contradiction. So the answer cannot be 1/2 (nor 1).

So none of the provided answer are correct. Therefore the probability of choosing the correct answer is 0