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 is the letter-cluster pair that 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.)

​Check each option:

A) KE → MF
K + 2 = M
E + 1 = F
(Follows) 

B) EY → GZ
E + 2 = G
Y + 1 = Z
​(Follows) ​

C) YS → AT
Y + 2 = A 
S + 1 = T
​(Follows) ​

D) PJ → RI
P + 2 = R
J + 1 = K (but given I)
Does not follow  

 Only option D (PJ → RI) does not follow the same alphabetical shifting pattern.

Thus, correct option is (d).