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 (a point). The undefined terms in geometry are point, line, and plane. A ray is a defined term (a part of a line with a fixed endpoint and extending infinitely in one direction). To define an angle, we use the undefined term "point" as the common endpoint of the two rays. A line is a straight path extending infinitely in both directions, and a plane is a flat surface extending infinitely, neither of which directly define an angle as a point does (as the vertex of the angle).

Answer:

C. point