Which of the following letter-number clusters will replace the question mark (?) in the given series to make it logically complete?
LOK 13, MON 12, NOQ 11, OOT 10, ?

Given: LOK 13, MON 12, NOQ 11, OOT 10, ?

Logic: 1st letter + 1, 2nd letter is same, 3rd letter + 3 and number - 1 place.

For, 1st letter

L + 1 = M, M + 1 = N, N + 1 = O, O + 1 = P

For, 3rd letter

K + 3 = N, N + 3 = Q, Q + 3 = T, T + 3 = W

For, number

13 - 1 = 12, 12 - 1 = 11, 11 - 1 = 10, 10 - 1 = 9

So, the missing term is POW 9.

Thus, correct option is (a).