Two Thin Layers of Material with Different Indices of Refraction

Multiple Choice

Two thin layers of material with different indices of refraction are coated on a glass plate.The outer first material has n₁ = 1.404,the inner second material has n₂ = 1.176,and the glass has n_glass = 1.62.If light is incident from air on the first layer,what is the phase change relative to that of the first layer reflection for light that reflects from the glass?

A) 180°
B) 540°
C) 360°
D) 0°