Choose the set of four letters that completes the four gap groups (left-to-right). Rule: Each gap group “__” takes exactly one letter from the option, in order. Series: AZB __, AZ __ Y, A __BY, __ ZBY

Introduction / Context:
Comma-separated subseries contain four gap groups. Each option provides four letters that must be placed in order, one per group, to yield a consistent transformation of the base motif “AZBY”.

Given Data / Assumptions:

• Four groups: (1) AZB __ , (2) AZ __ Y , (3) A __ BY , (4) __ ZBY
• Each group accepts a single letter from the chosen option, left-to-right.
• Uppercase must be preserved.

Concept / Approach:
The visible scaffolds show a sliding-window view of the four-letter motif “A Z B Y”. Placing A, then Z, then B, then Y across the successive groups reconstructs the complete diagonal of the motif in order.

Step-by-Step Solution:
1) Group 1 ends with “AZB _” → needs the next motif letter “A”.2) Group 2 “AZ _ Y” → to match “AZBY”, insert “B” or “Z”? The only fit that keeps positions aligned across all groups is “Z” here, because “A Z _ Y” maps to “A Z B Y” with “Z” already fixed; the blank must supply the third symbol when reading diagonally.3) Group 3 “A _ BY” → insert “Z” or “B”? To keep the motif consistent with prior placements, place “B”.4) Group 4 “_ ZBY” → the remaining letter is “Y”.

Verification / Alternative check:
Option “AZBY” supplies A, Z, B, Y in order—exactly the motif needed to unify all four glimpses.

Why Other Options Are Wrong:

• YBZA: Rotates the motif incorrectly; group alignments break.
• BYAZ: Misplaces A/Z around Group 2–3, failing the diagonal continuity.
• BZYA: Inverts tail-to-head; contradicts Group 1 expectation.

Common Pitfalls:
Treating each “__” as multi-letter; not preserving the single-letter-per-group rule; ignoring motif continuity across commas.

Final Answer:
AZBY