Which letter cluster will replace the question mark (?) to complete the given series?
ZVRN, VSPM, RPNL, ?, JJJJ

Correct option is D

Given ZVRN, VSPM, RPNL, ?, JJJJ

Breaking it down letter by letter:

1st letters: Z → V → R → ? → J ( - 4 pattern follows) 
2nd letters: V → S → P → ? → J ( - 3 pattern follows) 
3rd letters: R → P → N → ? → J ( - 2 pattern follows) 
4th letters: N → M → L → ? → J ( - 1 pattern follows) 

first letter of missing term is = R - 4 = N
second letter of missing term is = P - 3 = M
third letter of the missing term is = N - 2= L
fourth letter of the missing term is = L - 1= K

Missing term is NMLK