Fill in the blanks to complete the letter pattern: bc _ b _ c _ b _ ccb

Introduction / Context:
This verbal reasoning question deals with a letter series that hides a repeating block pattern. Candidates must carefully observe how short groups of letters recur and then insert the correct sequence into the blanks. Here the partially filled pattern is bc _ b _ c _ b _ ccb, and we must choose a four letter sequence to fill the blanks so that the whole series becomes consistent.

Given Data / Assumptions:
- Incomplete letter pattern: b c _ b _ c _ b _ c c b.- There are four blanks in total, and we must insert four letters in order.- Options give four letter groups such as cbcb, bbcb, cbbc and bcbc, which will be placed into the blanks from left to right.

Concept / Approach:
The best approach is to assume the pattern repeats some fixed block of letters. We test each option by substituting its letters into the blanks and then check whether the resulting full sequence can be partitioned into equal repeating blocks. The option which produces a perfect repetition throughout the length of the series is the correct answer.

Step-by-Step Solution:
- Write the pattern with placeholders: b c _ b _ c _ b _ c c b.- Now test option a: cbcb.- Fill the blanks in order with c, b, c, b.- The completed series becomes: b c c b b c c b b c c b.- Group the letters into blocks of four: (b c c b), (b c c b), (b c c b).- Each block is identical, giving a clean repetition of the pattern bccb.- This shows that option a creates a perfectly repeating structure across the entire string.

Verification / Alternative check:
- Test option b: bbcb. The resulting string does not break neatly into identical four letter blocks.- Test option c: cbbc and option d: bcbc similarly; each produces at least one block that differs from the others.- Only option a: cbcb yields three identical blocks bccb, confirming it as the unique correct choice.

Why Other Options Are Wrong:
- bbcb, cbbc and bcbc give patterns where some four letter segments differ from others, so the string cannot be described as a simple repetition of a single block.- This violates the usual expectation in such letter series questions where a short fixed pattern repeats.

Common Pitfalls:
- Candidates may try to reason only locally near each blank instead of observing the full repeated block.- It is easy to visually misread similar sequences like bccb and bcbc, leading to incorrect substitution.- Not grouping the letters into equal segments can make the repetition less obvious.

Final Answer:
Filling the blanks with the letters c, b, c, b gives a three time repetition of the block bccb, so the correct inserted group is cbcb.