Complete the letter series by filling the blanks left-to-right. Rule: Each "_" is one letter; use lowercase as shown. Series: g _ _ g _ _ gh _ g _ i

Introduction / Context:
This is a structured series completion task. We must fill six gap groups with one letter each, using the smallest deterministic rule that explains all fixed letters “g”, “h”, “i” placements.

Given Data / Assumptions:

• Stem groups: g _ _ | g _ _ | gh _ | g _ | i
• All blanks accept lowercase letters.
• There are 6 fills (X1..X6) read left-to-right.

Concept / Approach:
The visible scaffold “g … g … gh … g … i” suggests an interleave of the natural run g→h→i, where “h” clusters around each “g” and “i” marks the terminal escalation. A minimal rule: after each “g”, place “h” first; where a pair of blanks follow, alternate “h/i” to maintain growth towards the final “i”.

Step-by-Step Solution:
1) After the first “g__”, insert “h i”.2) After the second “g__”, again insert “h i”.3) In “gh_”, the only next minimal step is “i”.4) In “g_”, use “i” to maintain the rising approach to the terminal “i”.

Verification / Alternative check:
The fills “h i | h i | i | i” concatenate to “hihiih”, satisfying a consistent rising pattern and aligning the final anchor “... g _ i”.

Why Other Options Are Wrong:

• jkljkl: Introduces letters not supported by the scaffold and overshoots the g–h–i band.
• hhiiHH: Mixed casing and non-minimal repetition; violates lowercase constraint.
• hijklI: Unequal step sizes and casing issues; not a smallest consistent rule.

Common Pitfalls:
Confusing total underscores with number of gap groups; ignoring case uniformity; forcing long cycles when a short interleave suffices.

Final Answer:
hihiih