Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete?
OKI 4, QLG 8, SME 12, UNC 16, ?​

Correct option is B

Given - OKI 4, QLG 8, SME 12, UNC 16, ?​​

Logic - first letter + 2, second letter + 1, third letter -2 and number +4

Explanation (Letter-wise):
O + 2 = Q → Q + 2 = S → S + 2 = U → U + 2 = W
K + 1 = L → L + 1 = M → M + 1 = N → N + 1 = O
I – 2 = G → G – 2 = E → E – 2 = C → C – 2 = A

14 + 4 = 8, 8 + 4 = 12, 12 + 4 = 16, 16 + 4 = 20 
So the missing term = WOA 20
Final Answer:
The missing letter-number cluster is WOA 20
 Final Correct Option: (B) WOA 20