The definition of a circle uses the undefined term:

A. arc

B. line

C. plane

D. ray

Answer

B. line

Explanation

The definition of a circle uses the undefined term "line." A circle is defined as the set of all points in a plane that are equidistant from a given point, called the center. The term "line" is crucial in this definition because it helps describe the distance (radius) from the center to any point on the circle. Lines are considered undefined terms in geometry, forming the foundation of more complex definitions and theorems.