N, C
N, D
O, C
O, D
Answer is Wrong!
Answer is Right!
The correct answer is C. O, C.
The sequence is a simple alternating repetition of the letters Z, S, S, W, O, T, K, Q, G, O, C.
The first letter of each term is repeated, followed by the next letter in the alphabet. This pattern is repeated until the letter Z is reached, at which point the sequence starts over with the letter S.
The missing terms are therefore O and C.