What occurs when a light ray is turned back into the incident material?

When a light ray is turned back into the incident material, it is referred to as reflection. This phenomenon occurs at the boundary between two different media, where a certain portion of the light does not transmit into the second medium but instead bounces back into the first medium. The law of reflection states that the angle of incidence is equal to the angle of reflection, meaning the way light behaves at the surface reflects it back under the same angle it arrived at.

Refraction, on the other hand, is the bending of light rays as they pass from one medium to another at an angle, leading them to change speed and direction. Diffraction involves the spreading out of light waves as they pass through a small aperture or around obstacles, while absorption refers to the process where light is absorbed by a material rather than reflected or transmitted. Each of these processes serves different roles in the behavior of light, thus highlighting why reflection is the correct answer in the context of the question provided.