When Light in Air Strikes the Flat Surface of a Certain

Multiple Choice

When light in air strikes the flat surface of a certain glass at 31.2° with the normal, the reflected ray is 100 percent polarized. What is the critical angle for the air-glass interface of this glass?

A) $21.4 ^ { \circ }$
B) $68.6 ^ { \circ }$
C) $58.8 ^ { \circ }$
D) $52.7 ^ { \circ }$
E) $37.3 ^ { \circ }$