JEE Math Practice Question

Let A and B denote the statements A: $$\cos \alpha + \cos \beta + \cos \gamma = 0$$ B: $$\sin \alpha + \sin \beta + \sin \gamma = 0$$ If $$\cos \left( {\beta - \gamma } \right) + \cos \left( {\gamma - \alpha } \right) + \cos \left( {\alpha - \beta } \right) = - {3 \over 2},$$ then:

1. A.A is false and B is true
2. B.both A and B are true
3. C.both A and B are false
4. D.A is true and B is false