Question

which undefined term is used to define an angle?
line
plane
point
ray

Explanation:

An angle is defined as the figure formed by two rays sharing a common endpoint. The undefined terms in geometry are point, line, and plane. A ray is a defined term (formed from a point and a line segment). A line is a straight path, a plane is a flat surface. A point is an undefined term, and the common endpoint of the two rays forming an angle is a point. So the undefined term used to define an angle is point.

Answer:

C. point