Select the letter cluster that will replace the question mark (?) in the following series.

A, Z, X, B, V, T, C, R, ?, ?

P , D

The first, fourth and seventh letters are in alphabetical order. So, tenth letter would be the letter after C i.e. D.
Also, the second and third letters are alternate and in reverse order and so are the fifth and sixth letters and the eighth and ninth letters.