Answer: C) bend when passing from air to water.
Explanation:
Refraction is the phenomenon of bending of light when it passes from one medium to another.
Reflection is the phenomenon of bouncing back of light from a surface.
When light enters from air to water i.e it is moving from rarer to denser medium, it changes its original path as there is a change of speed of light and deflects itself towards the normal. This is known as the refraction of light and this is why a pencil in a cup of water looks as if it is broken and larger.