Consider the sequence AB_CC_A_BCCC_BBC_C that follows a certain pattern. Which one of the following completes the sequence?

1. A. B, C, B, C, A
2. B. A, C, B, C, A
3. C. B, C, B, A, C
4. D. C, B, B, A, C

Answer: C

Explanation

The given sequence is AB_CC_A_BCCC_BBC_C.
First, count the total number of characters, including the blanks. There are 18 positions.
We can try to divide the sequence into equal groups. Factors of 18 are 1, 2, 3, 6, 9, 18.
Let’s try grouping by 6 characters:
[AB_CC_] [A_BCCC] [_BBC_C]

By observing the existing characters, a repeating pattern of ‘ABBCCC’ seems plausible:
– In the first group [AB_CC_], if we fill the blank with ‘B’ and ‘C’, it becomes ABBCCC.
– In the second group [A_BCCC], if we fill the blank with ‘B’, it becomes ABBCCC.
– In the third group [_BBC_C], if we fill the blanks with ‘A’ and ‘C’, it becomes ABBCCC.

So, filling the blanks according to the ‘ABBCCC’ pattern:
AB**B**CC**C** | A**B**BCCC | **A**BBC**C**C

The missing letters, in order, are B, C, B, A, C. This matches option (c). This question tests pattern recognition and logical deduction skills, which are fundamental to the Logical Reasoning section of UPSC CSAT.