You still have a loop there.
As you said,
There are 2 parts:
1) What is the answer?
2) What chance do I have of randomly selecting it?
Right. So if the question-master arbitrarily selects a solution, let's say 25%, he can present four options in which "25%" is only offered once.
i.e. the answer is 25%, and the chance of selecting it is 25%. The two numbers are the same, so there is no loop and the question is valid, answerable by circling the appropriate letter.
For example, these sets of options...
A) 25% I A) 50%
B) 30% I B) 50%
C) 60% I C) 60%
D) 80% I D) 80%
... are both valid. In the first case, the question-master's answersheet says that 25% is the right answer, so A is correct. In the second, the question-master's answersheet says that 50% is the right answer, so A or B is correct.
In both cases, the percentage figure on the question-master's answersheet matches the percentage figure circled by the student - AND mathematically the probabilities are correct - in the first case, the chance of randomly selecting A)25% is 25%, and so on.
The question does not say to use A, B, C or D in the answer.
But that's how multiple-choice exams work. You circle the letter. That method works for the valid questions above.
I believe the answer is "25%". (Which is the chance of selecting B. out of the 4 options.)
In which case you can circle the appropriate letter, either A or D, which both say the answer is 25%.
And if you do so, your answer will be wrong, because you've decided that the question-master's answersheet says that B)50% is the right answer. As you said:
25% would be the correct answer except it is represented twice, increasing your odds to 50%.
So I'd say the answer to the question is B (50% chance).
So, if you think the answersheet says B, circling A or D will obviously be the wrong answer.
But B would also be wrong, because it is evident that the chance of choosing it randomly is 25%, not 50%, therefore the question-master's answer is mathematically wrong, and he has set an invalid problem.
I'm getting dizzy...