# A light ray is incident perpendicular to one face of a $90^{\circ}$ prism and is totally internally reflected at the glass-air interface. If the angle of reflection is $45^{\circ}$, we conclude that the refractive index $n$ <br> <img src="http://clay6.com/mpaimg/1167_a.jpg"/>
( A ) $n < \frac{1}{\sqrt{2}}$
( B ) $n > \frac{1}{\sqrt{2}}$
( C ) $n > \sqrt{2}$
( D ) $n < \sqrt{2}$