It is 33% if the answer itself is randomly chosen from 25%, 50%, and 60%. Then you have:
If the answer is 25%: A 1/2 chance of guessing right
If the answer is 50%: A 1/4 chance of guessing right
If the answer is 60%: A 1/4 chance of guessing right
And 1/3*1/2 + 1/3*1/4 + 1/3*1/4 = 1/3, or 33.333…% chance
If the answer is randomly chosen from A, B, C, and D (With A or D being picked meaning D or A are also good, so 25% has a 50% chance of being the answer) then your probability of being right changes to 37.5%.
This would hold up if the question were less purposely obtuse, like asking “What would be the probability of answering the following question correctly if guessing from A, B, C and D randomly, if its answer were also chosen from A, B, C and D at random?”, with the choices being something like “A: A or D, B: B, C: C, D: A or D”
It is 33% if the answer itself is randomly chosen from 25%, 50%, and 60%. Then you have:
If the answer is 25%: A 1/2 chance of guessing right
If the answer is 50%: A 1/4 chance of guessing right
If the answer is 60%: A 1/4 chance of guessing right
And 1/3*1/2 + 1/3*1/4 + 1/3*1/4 = 1/3, or 33.333…% chance
If the answer is randomly chosen from A, B, C, and D (With A or D being picked meaning D or A are also good, so 25% has a 50% chance of being the answer) then your probability of being right changes to 37.5%.
This would hold up if the question were less purposely obtuse, like asking “What would be the probability of answering the following question correctly if guessing from A, B, C and D randomly, if its answer were also chosen from A, B, C and D at random?”, with the choices being something like “A: A or D, B: B, C: C, D: A or D”