What is the index of refraction?

a. the ratio of the speed of light in a vacuum to the speed of light in the material it is passing though

b. the amount the light ray has bent toward the normal line when entering a new medium

c. the difference between the angle at which the light ray enters the new medium and the angle at which it is reflected

d. the percentage that the light ray bent when it entered the new medium

a. the ratio of the speed of light in a vacuum to the speed of light in the material it is passing though    

Explanation:

When a light ray enters from one medium to another, it bends. This is because the speed of light decreases as it enters a medium having more optical density. The speed of light is maximum in vacuum.

The refractive index determines the optical density of a medium. It is the ratio of the speed of light in the vacuum (c) to the speed of light in the material it is passing through (v).

where's the following? you gotta add it to know what the choices are

explanation:

if they have a finite resultant