The correct answer is A. O, P.
The sequence is a simple alternating repetition of the letters C, F, I, L, O, V, and X. The first letter of each pair is followed by the next letter in the alphabet, and the second letter of each pair is repeated.
C is followed by F, which is followed by I, which is followed by L. The second letter of each pair is repeated, so the second letter of the third pair is also L. This continues until we reach the letter X, which is followed by O. The second letter of the last pair is P, so the answer is O, P.
Option B is incorrect because P is not followed by Q in the alphabet. Option C is incorrect because R is not followed by R in the alphabet. Option D is incorrect because S is not followed by R in the alphabet.