Answer: The correct option is A.
Step-by-step explanation:
Refraction is the phenomenon in which there is a change in the direction of the light wave when it passes from one medium to another.
It is caused due to the change in the speed of the wave.
Refraction phenomenon occurs in the lens.The light ray is refracted when it passes through the lens.
Therefore, when a wave travels from one medium to another, it changes the speed.