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

Logic: ​Each letter pair has a difference of +4 in alphabetical positions.

Let's check options:

N +4  →R

M +4 → Q

Option B: EI - DH 

E +4 → I

D +4 → H

Option C: RV - QU

R +4 → V

Q +4 → U

X +2 → Z

T -8 → L

So, Option D (XZ - TL) does NOT follow that.

Thus, the correct option is: (d)