Find the missing letters in the following sequence in the correct order abca bcaab ca bbc

Question

Find the missing letters in the following sequence in the correct order

abca bcaab ca bbc

1. A. ccaa
2. B. abac (Correct answer)
3. C. abba
4. D. bbaa

Correct Answer

Option B — abac

Detailed Solution & Explanation

The correct answer is abac.

Key Points

• The sequence is abca_bcaab_ca_bbc_, with four blanks to be filled in order.
• Filling them with a, b, a, c gives the complete string: abcaabcaabbcaabbcc.
• That string breaks into a progressive pattern of four groups, each one letter longer than the last:
  • abc (3 letters)
  • aabc (4 letters) — one extra *a*
  • aabbc (5 letters) — one extra *a* and *b*
  • aabbcc (6 letters) — one extra *a*, *b* and *c*
• Each group repeats the letters a, b, c in order, with the count of each letter building up step by step.

Additional Information

• Testing the other options confirms the answer: only abac produces the clean 3-4-5-6 progression. Option A gives *acbc / aabcc*, Option C gives *abbbca* and Option D gives *abbc / aabbca* — none of which forms a consistent pattern.
• The efficient technique for letter-series questions is to write the full string out first, then look for grouping boundaries, rather than trying to reason about the blanks in isolation.