The sum of all possible values of $$\theta \in [0, 2\pi]$$, for which the system of equations :
$$x\cos 3\theta - 8y - 12z = 0$$
$$x\cos 2\theta + 3y + 3z = 0$$
$$x + y + 3z = 0$$
has a non-trivial solution, is equal to :

A

$$\pi$$

B

$$2\pi$$

C

$$3\pi$$

D

$$4\pi$$