A Light Ray Passes from Air Through a Thin Plastic

Multiple Choice

A light ray passes from air through a thin plastic slab (n = 1.34) with parallel sides.If the ray in air makes an angle of 33° with the normal after leaving the slab,what is the angle of incidence for the ray in air as it impinges upon the other side of the slab?

A) 24°
B) 33°
C) 18°
D) 25°
E) ​44°