Or, if you're arbitrarily choosing A) B) C) or D), you have a 50% chance of choosing 25%, and a 25% chance of choosing 50%. The intuitive answer is 25% in a four-choice multiple choice, which would make 50% the correct answer (since there are two 25% answers), but in that case the answer is 25% (since only one answer says 50%), but... so on and so forth.

If D) was something different there are a few interesting possibilities -- if D) is 0% you could toy with the idea that none of the answers are correct (we haven't actually established that any of the answers are correct), except that it would make D) correct, making it incorrect, so A) would have to be correct because one of the answers other than D) must be correct.

If D) was 50% then I'd say any answer other than C) is correct, kind of. There's only one 25%, and if it's deemed "correct", then there's a 25% chance of picking it. But with two 50%s, there's a 50% chance of picking that, so it could be "correct". Is its correctness determined by you picking it and then deciding if it holds true for it to be correct? Then you have a 75% chance of picking a correct answer and none of them are correct. Unless C) was 75%. Then I think we get another paradox.

Then again, I'm not very good at probabilities, and have been wrong here before