Which of the following phrases defines the angle of refraction?
a.
the angle between the incident ray and the normal
b.
the angle between the incident ray and the refracted ray
c.
the angle between the substance’s surface and the incident ray
d.
the angle between the refracted ray and the normal

Explanation:

Refraction is defined as the phenomenon of bending or changing course of a light ray when it passes from one medium to another medium.

The new ray formed after the bending at the surface of new medium is called the refracted ray.

The angle between the refracted ray and the normal of the point on the surface of the new medium where the ray enters is called angle of refraction.

Refer the attachment for instance.

In short,it is the angle between the refracted ray and the normal.