Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.
RIN, TFR, VCV, ?, ZWD
Answer & explanation
Correct answer: option 4

Explanation:
RIN, TFR, VCV, ?, ZWD
The logic followed here is :
R → (+2) → T → (+2) → V → (+2) → X → (+2) → Z
I → (-3) → F → (-3) → C → (-3) → Z → (-3) → W
N → (+4) → R → (+4) → V → (+4) → Z→ (+4) → D
So, the letter-cluster that replaces the (?) to complete the series is "XZZ"