Fact 1: Water causes refraction of light.

Fact 2: Refraction is the bending which is caused by changing speed.

Given the two facts above, answer the question "What aspect of light changes when it enters water?" with the following options: 
- Energy.
 - speed
 - kinetic
 - seasons
 - reacts
 - energy
 - heat
 - mostly


 

  speed       