Three flat layers of transparent material are stacked upon one another. The top layer has index of refraction n₁, the middle has n₂ and the bottom one has n₃. If n₁ > n₂ > n₃, and if a ray of light strikes the top layer at an angle of incidence _i = 30, in which layer is the angle of refraction the greatest?

a. the top layer

b. the middle layer

c. the bottom layer

d. once the ray enters the touching layers, the angle of refraction remains constant.