There are four statements X, Y, Z and W. Their relations are as follows : If X is incorrect, then so is Z; if Y is incorrect, then W is correct; if W is correct, then X is incorrect. Which of the following is/are correct? I. If X is correct, then so is Y. II. If Z is correct, then it is not necessary that Y is correct. Select the answer using the code given below.
- (a) I only ✓ UPSC's answer
- (b) II only
- (c) Both I and II
- (d) Neither I nor II
Why the answer is (a)
• The given rules are: X incorrect → Z incorrect; Y incorrect → W correct; W correct → X incorrect.
• I: suppose X is correct. By the third rule W cannot be correct, so W is incorrect. By the second rule, if Y were incorrect W would be correct, so Y must be correct. I holds.
• II: suppose Z is correct. By the first rule X cannot be incorrect, so X is correct, and then (as in I) Y is correct. So Y is necessarily correct and II is false.
• Hence I only: (a).
Why the other options are wrong
- (b) II only
- II is false: Z correct forces X correct and then Y correct.
- (c) Both I and II
- II is false.
- (d) Neither I nor II
- I follows from the rules.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2026, held on 24 May 2026. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.