Question

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

Explanation:

In geometry, a circle is defined as the set of all points in a plane that are at a given distance from a given point (the center). Here, “plane” is an undefined term in geometry. An arc is a part of a circle (a defined term). A line is a straight one - dimensional figure (a defined term in geometry in terms of other concepts). A ray is a part of a line that starts at a point and extends infinitely in one direction (a defined term). So the undefined term used in the definition of a circle is “plane”.

Answer:

C. plane