i don't get it... maybe i'm being incredibly dense but it looks like it should be B. this makes the correct answer 25%, so the probability of getting it right at random is 50% because 2 out of 4 answers are 25% - so the answer is B = 50%, and indeed the chance of choosing B is 25%

answering the question at random is not the same as answering the question posed - so the fact that the two answers are not equal shouldn't be a problem. right?

edit: i hate paradoxes, i'm pretty certain i'm wrong, but i can't put my finger on precisely why. :)