D is correct. Ā This has to do with the frequency dependence of the index of refraction. Ā This effect can be seen in prisms and is what allows them to break white light into its different colors (frequencies). Ā If they all bent the same amount, the beam would stay together and the light leaving a prism would remain white. Ā Also rainbows would not be possible, since they are made by light refracting at different angles inside spherical droplets of water in the earth's atmosphere.
