Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.

CUH, HQK, MMN, RIQ, ?

WET

Explanation:

CUH, HQK, MMN, RIQ, ?

The logic followed here is :

C → (+5) → H → (+5) → M → (+5) → R → (+5) → W

U → (-4) → Q → (-4) → M → (-4) → I → (-4) → E

H → (+3) → K → (+3) → N → (+3) → O → (+3) → T

So, the letter-cluster that replaces the (?) to complete the series is "WET"