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

TOM, UMP, VKS, ?, XGY

WIV

Explanation:

TOM, UMP, VKS, ?, XGY

The logic followed here is :

T → (+1) → U → (+1) → V → (+1) → W → (+1) → X  

O → (-2) → M → (--2) → K → (-2) → I → (-2) → G  

M → (+3) → P → (+3) → S → (+3) → V → (+3) → Y 

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