Question

the definition of a circle uses the undefined term ______.
arc
line
plane
ray

Explanation:

To solve this, we recall the definition of a circle and undefined terms in geometry. A circle is defined as the set of all points in a plane that are equidistant from a given point (the center). The term "plane" is an undefined term in geometry (along with point and line, but here we analyze the options). "Arc" is a part of a circle, "line" is a different undefined term but not used in the basic circle definition as directly as plane, and "ray" is a part of a line. So the undefined term used in the circle's definition is plane.

Answer:

C. plane