What should come in place of the question mark (?) in the given series based…

A letter-series analogy built on English alphabet positions is governed by a fixed pair of position-offsets that turns a group's base letter into its next two letters (base, base+d1, base+d1+d2); the base letters of successive groups themselves change by their own constant step. Recovering the answer means fixing both the internal offset pair from the given groups and the base-letter step, then applying both to the next base letter.

1. Convert each given group to alphabet positions (A=1 ... Z=26): LOQ -> L=12, O=15, Q=17; internal offsets 15-12=3 and 17-15=2, i.e. (+3, +2).

2. JMO -> J=10, M=13, O=15; offsets 13-10=3 and 15-13=2, i.e. (+3, +2).

3. HKM -> H=8, K=11, M=13; offsets 11-8=3 and 13-11=2, i.e. (+3, +2).

4. FIK -> F=6, I=9, K=11; offsets 9-6=3 and 11-9=2, i.e. (+3, +2). All four groups use the same internal offset pair, (+3, +2), confirming the rule.

5. Compare the base (first) letters of successive groups: L=12, J=10, H=8, F=6 — each base is 2 less than the one before.

6. Applying that same step to the last given base: next base = F(6) - 2 = 4, which is D.

7. Apply the internal offset pair (+3, +2) to base D(4): D(4) -> next letter = 4+3 = 7 = G -> next letter = 7+2 = 9 = I.

8. So the missing group of letters is D, G, I.

Cross-check: for D(4), G(7), I(9), the internal offsets are 7-4=3 and 9-7=2, matching the (+3, +2) pattern found in every other group, and the base 4 is exactly 6-2, consistent with the base-letter step. Both conditions the rule requires are satisfied, so the missing group is DGI.