What should come in place of the question mark (?) in the given series based on the English alphabetical order?
ABC, CDE, EFG, GHI, ? , KLM

Given: ABC, CDE, EFG, GHI, ?, KLM

Logic: Each letter is increasing by + 2 in alphabetical order.

A → C → E → G → I → K
A + 2 = C
C + 2 = E
E + 2 = G
G + 2 = I
I + 2 = K

B → D → F → H → ? → L
B + 2 = D
D + 2 = F
F + 2 = H
H + 2 = J
J + 2 = L

C → E → G → I → ? → M
C + 2 = E
E + 2 = G
G + 2 = I
I + 2 = K
K + 2 = M

Thus, the correct option is (a) IJK.