In the series _b_a_ba_b_abab_aab; fill in the six blanks ( _ ) using one of the following given four choices such that the series follows a specific order.
- (a) bababa
- (b) baabba
- (c) bbaabb
- (d) ababab ✓ UPSC's answer
Why the answer is (d)
• Fill the six blanks in order with a, b, a, b, a, b (option d): the series becomes abbaab abbaab abbaab.
• It is the block 'abbaab' repeated three times, a clear pattern.
• The other choices give strings with no repeating block (for example, option (a) gives bbaabbaabbababaaab).
• Hence option (d).
Why the other options are wrong
- (a) bababa
- bababa gives bbaabbaabbababaaab, which has no repeating block.
- (b) baabba
- baabba gives bbaaababbbababaaab, which has no repeating block.
- (c) bbaabb
- bbaabb gives bbbaabaabbababbaab, which has no repeating block.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2021, held on 10 October 2021. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.