Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
K _ C T Q _ O C _ _ K O _ T _ K O _ T T

A

O, K, T, R, C, T, C

B

P, K, T, R, C, S, C

C

O, K, U, R, C, S, C

D

O, K, T, R, C, S, C