Based on the English alphabetical order, three of the following four letter-clusters are alike in a certain way and thus form a group. Which letter-cluster does not belong to that group?
(Note: The odd letter-cluster is not based on the number of consonants/vowels or their position in the letter-cluster.) ​​

Logic: All clusters follow the pattern +3, +2 in alphabet order.

​Option A. FIK

F + 3 → I

I + 2 → K

Option B. JMP

J + 3 → M

M + 2 → O $$\not=$$ P

Option C. ORT

O + 3 → R

R + 2 → T

Option D. DGI

D + 3 → G

G + 2 → I

All clusters except JMP follow the pattern +3, +2.

So, the odd one is: JMP

Thus, the correct option is: (b)