The Figure Shows a Point Source of Unpolarized Light at a Inside

Multiple Choice

The figure shows a point source of unpolarized light at A inside a uniform transparent crystal. The ray AO in the crystal strikes the plane surface SS' making an angle of 30° with the normal. This angle is the critical angle for transmission into air.

-For what angle of incidence will the reflected rays of light be completely polarized?

A) 15°
B) 27°
C) 30°
D) 60°
E) 63°