When Light Passes from a Material with a High Index $\degree$

When light passes from a material with a high index of refraction into material with a low index of refraction:

A) none of the light is reflected.
B) some light is reflected without a change of phase.
C) some light is reflected with a 180 $\degree$ change of phase.
D) the light that is not reflected has a 180 $\degree$ change of phase.