A Ray of Light Enters an Equilateral Prism Made of Material

Multiple Choice

A ray of light enters an equilateral prism made of material with n = 1.45 at an angle of incidence $\theta$ . The internally refracted ray is parallel to the base of the prism.What is the angle of refraction for the ray leaving the prism?

A) 46.5 $^{\circ}$
B) 30.0 $^{\circ}$
C) 20.2 $^{\circ}$
D) 15.7 $^{\circ}$
E) the ray won't leave the prism