When a Beam of Light That Is Traveling in Air $45 ^ { \circ }$

When a beam of light that is traveling in air is reflected by a glass surface, there is

A) a $45 ^ { \circ }$ phase change in the reflected beam.
B) a $180 ^ { \circ }$ phase change in the reflected beam.
C) a $90 ^ { \circ }$ phase change in the reflected beam.
D) no phase change in the reflected beam.
E) a $60 ^ { \circ }$ phase change in the reflected beam.