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

BOND, FKRZ, JGVV, NCZR, ?

RYDN

Explanation:

BOND, FKRZ, JGVV, NCZR, ?

The logic followed here is :

B → (+4) → F → (+4) → J → (+4) → N → (+4) → R  

O → (+4) → K → (+4) → G → (+4) → C → (+4) → G  

N → (+4) → R → (+4) → V → (+4) → Z → (+4) → D 

D → (-4) → Z → (-4) → V → (-4) → R → (-4) → N

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