The correct answer is (a) P, D.
The sequence is a simple alternating repetition of the letters of the alphabet, starting with A and Z, and then X and B, and so on. The next two letters in the sequence are P and D.
(b) E and O are not the next two letters in the sequence because they are not in the correct order. The letters in the sequence alternate between being in alphabetical order and being in reverse alphabetical order.
(c) Q and E are not the next two letters in the sequence because they are not in the correct order. The letters in the sequence alternate between being in alphabetical order and being in reverse alphabetical order.
(d) O and Q are not the next two letters in the sequence because they are not in the correct order. The letters in the sequence alternate between being in alphabetical order and being in reverse alphabetical order.