Select the option that represents the letters that, when placed from left to right in the same sequence in the blanks below; will complete the letter series.
C_PR_DT_RN_T_RN_TP_N

Given
The incomplete letter series is: C_PR_DT_RN_T_RN_TP_N.

By option A: T N P E P F R

C T PR N DT P RN E T P RN F TP R N.

By option B: T P N D P F R

C T PR P DT N RN D T P RN F TP R N.​

​(Doesn't follows the logical pattern)​

By option C: T N T E P F P

C TPR N DT TRN E T P RN F TP P N.

​(Doesn't follows the logical pattern)​

By option D: P N P E R F P

C   D   PR N DT P RN E T R R N F TP P N.

​(Doesn't follows the logical pattern)​

Thus, correct option is (a).