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.

-If point A is 16 cm below the plane SS',what is the radius of the largest circle at the air-crystal interface through which light can emerge from the crystal?

A) 9.2 cm
B) 16.0 cm
C) 18.4 cm
D) 27.0 cm
E) 32.0 cm