What should come in place of the question mark (?) in the given series based on the English alphabetical order?

BDF, HJL, NPR,  ? , ZBD

​BDF, HJL, NPR,  ? , ZBD

Logic: ​Each letter in the group increases by +6 alphabet positions.

First Letter: B +6 → H, H+6 → N, N+6 → T, T+6 →Z

Second Letter: D +6 → J, J +6 → P, P +6 → V, V +6 → B

Third Letter: F +6 → L, L +6 → R, R +6 → X, X +6 → D

So, the missing term is: T V X

Thus, the correct option is: (a)