Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
U A _ B _ T U _ C B D _ _ A C B _ T U A C _ _ T

A

C, D, A, U, U, D, B, D

B

C, D, A, T, U, D, C, D

C

D, C, A, T, U, D, D, B

D

C, D, A, T, U, D, B, D