Complete the pair :
BNLP : YMOK :: KGDU : ?

​BNLP : YMOK :: KGDU : ?

Logic: Replace each letter with its alphabetical opposite (A↔Z, B↔Y, …).

B ↔ Y

N ↔ M

L ↔ O

P ↔ K

Now apply same for KGDU : ?

K ↔ P

G ↔ T

D ↔ W

U ↔ F

So, KGDU : PTWF

Thus, the correct option is:  B