The diagram below illustrates the law of reflection.

A horizontal line labeled Mirror has an arrow labeled Incoming Light from up and left strike it at a point, and then another arrow arises at that point and goes up and right. A dotted line divides the angle made by the 2 arrows in half. A is the angle from the mirror to Incoming Light. B is the angle from Incoming Light to the dotted line. C is the angle from the dotted line to the second arrow. D is the angle from the second arrow to the Mirror.

According to the law of reflection, which statement must be true?

The measure of angle A equals the measure of angle B.
The measure of angle B equals the measure of angle C.
The measure of angle A equals the measure of angle C.
The measure of angle B equals the measure of angle D.