Please solve this question :

Let A and B denote the statements
A: cos α + cos β + cos γ = 0
B: sin α + sin β + sin γ = 0

If $\cos (\beta - \gamma ) + \cos (\gamma - \alpha ) + \cos (\alpha - \beta ) = -\frac{3}{2}$, then :
(1) A is false and B is true
(2) both A and B are true
(3) both A and B are false
(4) A is true and B is false