Fill the blanks with one letter per gap group, left-to-right. All letters are lowercase as shown. Series: oopqop _ qoo _ qo _ oqo _ pq

Introduction / Context:
The visible text shows frequent “o”, “p”, “q” in a woven cadence. Our goal is to choose a four-letter sequence, one character per gap group, that sustains a consistent minimal-cycle weave across the entire string.

Given Data / Assumptions:

• Stem: “oopqop _ qoo _ qo _ oqo _ pq”
• Gap groups: 4 (X1..X4), one lowercase letter per group.
• Alphabet involved: {o, p, q} only.

Concept / Approach:
We identify a repeating micro-block “op” interleaved with “q” as separator. The anchors “…opqop… qoo … qo … oqo … pq” indicate that inserting “o p o p” at the four gaps maintains alternating “o/p” around each “q”-anchored subphrase.

Step-by-Step Solution:
1) After “…op”, supply “o” to extend an “opo” loop.2) Before “…qoo…”, insert “p” to keep “op” alternation.3) Before “…qo…”, insert “o” maintaining symmetry around “q”.4) Before “…pq”, insert “p” to land on a closing “…opq”.

Verification / Alternative check:
Fills “o p o p” yield a smooth “op” alternation with embedded “q” separators. No anchor conflicts appear.

Why Other Options Are Wrong:

• oppo: Duplicates “p” mid-run; disturbs alternation.
• popo: Inverts the start and breaks the first “…op” adjacency.
• poop: Creates adjacent “oo” in places reserved for “op” cadence.

Common Pitfalls:
Miscounting gap groups; inserting multiple letters per group; ignoring adjacency constraints around “q”.

Final Answer:
opop