The value of $$\frac{(x -y)^{3} + (y - z)^{3} + (z - x)^{3}}{6(x -y)(y - z)(z - x)}$$, where $$x \neq y \neq z$$, is equal to:

A

$$\frac{1}{4}$$

B

$$\frac{1}{2}$$

C

$$\frac{1}{3}$$

D

$$\frac{1}{9}$$