Four letter-clusters have been given, out of which three are alike in some manner and one is different. Select the odd one.

From the given options 

Logic: (+6, -7)
H(8), L(12), G(7) → Differences: (+4, -5)
K(11), Q(17), J(10) → Differences: (+6, -7)
R(18), X(24), Q(17) → Differences: (+6, -7)
C(3), I(9), B(2) → Differences: (+6, -7)
Identifying the Odd One
The patterns KQJ, RXQ, and CIB follow the same (+6, -7) sequence.
HLG follows a different pattern (+4, -5).

Correct answer is (a)