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.)​

From the given options : 

Logic: Pattern: Both letters decreased by 2

(A) JN – HL
J = 10 → H = 8 (−2)
N = 14 → L = 12 (−2)
(B) LP – JK
L = 12 → J = 10 (−2)
P = 16 → K = 11 (−5) Mismatch in pattern (−2, −5)
(C) NR – LP
N = 14 → L = 12 (−2)
R = 18 → P = 16 (−2)
(D) OS – MQ
O = 15 → M = 13 (−2)
S = 19 → Q = 17 (−2)

Correct answer is (b) LP – JK.