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

WUW, TSV, QQU, NOT, ?

KMS

Explanation:

WUW, TSV, QQU, NOT, ?

The logic followed here is :

W → (-3) → T → (-3) → Q → (-3) → N → (-3) → K

U → (-2) → S → (-2) → Q → (-2) → O → (-2) → M

W → (-1) → V → (-1) → U → (-1) → T → (-1) → S

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