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

CBDD, EBBD, ?, IBXD, KBVD

Logic: 1st +2, 2nd same , 3rd -2 and 4th same

1st Position (C, E, ?, I, K):

C + 2 → E

E + 2 → G

G + 2 → I

I + 2 → K

2nd Position (B, B, ?, B, B):

The letter in this position remains B throughout the sequence.

3rd Position (D, B, ?, X, V):

D - 2 → B

B - 2 → Z

Z - 2 → X

X - 2 → V

4th Position (D, D, ?, D, D):

The letter in this position remains D throughout the sequence.

The missing cluster is GBZD.

Thus, correct option is (d).