# Consider <br> $f(x) = \tan^{-1} \begin{pmatrix} \sqrt{\frac{1+\sin x}{1 - \sin x}} \end{pmatrix}, x \in (0, \frac{\pi}{2})$. A normal to $y = f(x)$ at $x = \frac{\pi}{6}$ also passes through the point :
( A ) $(\frac{\pi}{6}, 0)$
( B ) $(0, \frac{2 \pi}{3})$
( C ) $(\frac{\pi}{4}, 0)$
( D ) $(0, 0)$