According to the law of reflection the angle of incidence is equal to the angle of blank

The answer should be:

Angle Of incidence is equal to angle of reflection.

The word that goes into the blank is reflection.

Explanation:

Angle of incidence is the angle made by the ray with the normal to the surface it hits and angle of reflection is the angle made by ray with the normal to the surface after it gets reflected from the surface.

As per law of reflection,

Angle of incidence = Angle of reflection