Final answer:
The statement that an angle has a unique bisector is true; there is only one straight line that can divide an angle into two equal smaller angles.
Step-by-step explanation:
The assertion that the angle bisector of an angle is unique refers to the concept that a given angle can have only one bisector that divides the angle into two equal smaller angles. This holds true for simple geometric angles. When you have an angle, there is exactly one straight line that can be drawn from the angle's vertex to some point on the angle itself that cuts the angle exactly in half. Therefore, the statement 'Angle bisector of an angle is unique' is true. This principle is fundamental in geometry and is useful in various geometric constructions and proofs.