If $$a + b + c = 0$$, then $$\frac{1}{x^a + x^{-b} + 1} + \frac{1}{x^b + x^{-c} + 1} + \frac{1}{x^c + x^{-a} + 1} =$$

A

$$x^{a + b + c}$$

B

$$x^{abc}$$

C

1

D

0