I hate to admit it but …
View attachment 54951
There is a 25% chance of picking each of the four answers, a, b, c, or d. But as a and d have the same value, there's a 50% chance of picking "25%", which (as 25≠50) would be wrong; A 25% chance of picking 50% which (as 50≠25) would be wrong; And a 25% chance of picking "0%", which (as 25≠0) would be wrong.
Any
randomly selected answer must therefore be wrong, so the correct answer is c) 0%. However, this now means that there
is a correct answer, which has a 25% chance of being selected at random, and (as 25≠0), that answer is wrong.
The correct answer is therefore that there is no correct answer; The question is malformed and impossible to answer within the usual paradigm of a multiple choice question, due to the liar's paradox.
If the correct answer is c, then c is incorrect; But if c is incorrect, then the correct answer is c.
The student cannot answer correctly within the usual constraints of multiple choice; Therefore the examiner is breaking the constraints, and the student should feel free to also disregard them.
^That would be my answer, though it might not fit in the available space on the answer sheet.