One face of the glass prism is silver polished. A light ray falls at an angle of $45^{\circ}$ on the other face. After reflection it is subsequently reflected from the silvered face and then retraces its path. The refracting angle of prism is $30^{\circ}$. The refractive index of the prism is :

Question

( A ) $\sqrt{3}$
( B ) $\frac{3}{2}$
( C ) $\sqrt{2}$
( D ) $\frac{\sqrt{3}}{2}$