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

RAT, UEY, XID, ?, DQN

AMI

Explanation:

RAT, UEY, XID, ?, DQN

The logic followed here is :

R → (+3) → U → (+3) → X → (+3) → A → (+3) → D

A → (+4) → E → (+4) → I → (+4) → M → (+4) → Q

T → (+5) → Y → (+5) → D → (+5) → I → (+5) → N

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