If $$\alpha, \beta, \gamma$$ are the roots of equations $$X^3 + Px^2 + qx + p = 0$$, Then the value of $$\tan^{-1} \alpha + \tan^{-1} \beta + \tan^{-1} \gamma$$ is

A

$$\frac {n \pi}{2}$$

B

$$n \pi$$

C

$$2 n \pi$$

D

$$\frac{n \pi}{4}$$