The answer for the problem is the option C, which is: C. Angle Bisector Theorem.
The explanation is shown below:
By definition, a bisector of a angle is the line that bisects an angle, or in other words, it is a line that passes through a vertex and cut it into two angles that have the same measure. Keeping this on mind, if a point is located on the bisector of an angle, then this point is equidistant from the two sides of the angle, this means that the distance between the point and the two sides are equal.