Correct Answer: glass to water

Solution : The correct option is glass to water.

The angle of incidence of a light beam passing from a denser medium to a less dense medium must be larger than the critical angle for total internal reflection to take place.  The incidence angle past which there is complete internal reflection is known as the critical angle. It depends on the refractive indices of the two media involved. So if light travels from glass (denser medium) to water (less dense medium) and the angle of incidence is greater than the critical angle for that combination of media, total internal reflection will occur.