Consider the sequence AB_CC_A_BCCC_BBC_C that follows a certain pattern. Which one of the following completes the sequence?
Answer & explanation
Answer: (c) B, C, B, A, C
The 18-letter series is the block ABBCCC written three times. Filling the five blanks to fit this block gives B, C, B, A, C.
- The series has 18 places. Split it into three blocks of six: AB_CC_ | A_BCCC | _BBC_C.
- The middle block A_BCCC suggests the repeating block ABBCCC.
- Fill every block as ABBCCC: first block needs B and C, second needs B, third needs A and C.
- In order the blanks are B, C, B, A, C.
- Check: ABBCCC ABBCCC ABBCCC.
Remember · For letter series with blanks, count the length, try equal blocks, and start from the most complete block.
Question and answer: UPSC's official GS Paper II (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·