Correct option is A
Logic: -3, -3

QNL (17, 14, 12) - Decreasing order (-3, -2)
ROL (18, 15, 12) - Decreasing order (-3, -3)
WTQ (23, 20, 17) - Decreasing order (-3, -3 )
LIF (12, 9, 6) - Decreasing order (-3, -3)
QNL is alike in this way (-3, -2).
Correct answer is (a).