$\int \frac{dx}{\cos x + \sqrt{3} \sin x}$ equals :

Question

( A ) $\frac{1}{2} \log \tan(\frac{x}{2} + \frac{\pi}{12} ) + c$
( B ) $\log \tan(\frac{x}{2} - \frac{\pi}{12} ) + c$
( C ) $\frac{1}{2} \log \tan(\frac{x}{2} - \frac{\pi}{12} ) + c$
( D ) $\log \tan(\frac{x}{2} + \frac{\pi}{12} ) + c$