Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete?

FJN 45, DHL 40, BFJ 35, ZDH 30, XBF 25, ?

Given: FJN 45, DHL 40, BFJ 35, ZDH 30, XBF 25, ?

Logic: Letters are decreasing - 2 and number is decreasing - 5 place.

For, letter

F - 2 = D, D - 2 = B, B - 2 = Z, Z - 2 = X, X - 2 = V

J - 2 = H, H - 2 = F, F - 2 = D, D - 2 = B, B - 2 = Z

N - 2 = L, L - 2 = J, J - 2 = H, H - 2 = F, F - 2 = D

For, number

45 - 5 = 40, 40 - 5 = 35, 35 - 5 = 30, 30 - 5 = 25, 25 - 5 = 20

So, the missing term is VZD 20.

Thus, correct option is (a).