Choose the 4-letter fill that preserves the alternating density of b/c around stable “ccbab … caa … bccc … a …” anchors: ccbab _ caa _ bccc _ a _
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Ababc
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Bbabb
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Cbbba
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Dbaab
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ENone of these
Answer
Correct Answer: babc
Explanation
Introduction / Context:The anchors “ccbab”, “caa”, “bccc”, and “a” suggest an alternation of b and c around fixed clusters. The correct 4-letter fill should keep a balanced b/c density without producing triple runs or disrupting the anchor shapes.
Given Data / Assumptions:
- Template: ccbab _ caa _ bccc _ a _
- Four letters are inserted sequentially.
- We must avoid “bbb” or “ccc” triple runs at the seams.
Concept / Approach:Pick a fill that starts with b (to pair after “…ccbab”), introduces an a only where a is already anchored, and alternates b/c on each side of “bccc”.
Step-by-Step Solution:
Choose “babc”.Seams: “…ccbab b caa b bccc b a b” keep alternation and avoid triples.The mid “a” is restricted to its anchor neighborhood, preserving structure.Verification / Alternative check:Other choices either cause “bbb/ccc” near anchors or place “a” in disruptive positions.
Why Other Options Are Wrong:
- babb: Creates “bbbb” risk close to “…bccc”.
- bbba: Triple b appears against “bccc”.
- baab: Misplaces “a” away from its anchor, breaking symmetry.
- None of these: Not necessary since “babc” fits.
Common Pitfalls:Inserting extra “a” far from “caa” anchor; overlooking triple-seam collisions.
Final Answer:babc