The factors of $$a^{2} - 1-2x - x^{2}$$ are ____________.

A

(a - x - 1) (a - x - 1)

B

(a + 1 + x) (a - 1 - x)

C

(a - x + 1) (a - x + 1)

D

(a - x + 1) (a - x - 1)