By definition, when the speed of the light changes when it passes from a material to another, this is called "Refraction of light". This happens when there is a difference in the index of refraction between both mediums o materials. Therefore, that speed depends of the medium through it passes.
The index of refraction is expressed as below:
n=c/v
"n" is the index of refraction.
"c" is is the speed of light.
"v" is the phase velocity of light in the medium.
A prism, a magnifying glass, a microscope, and eyeglasses refract light. Therefore, the correct option is: B) They refract light.
