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# Let A and B denote the statements <br> A : $\cos \alpha + \cos \beta + \cos \gamma = 0$ <br> $B: \sin \alpha + \sin \beta + \sin \gamma = 0$ <br> If $\cos (\beta-\gamma) + \cos(\gamma - \alpha) + \cos (\alpha - \beta) = -\frac{3}{2}$, then

( A ) both A and B are false
( B ) A is true and B is false
( C ) both A and B are true
( D ) A is false and B is true