Answer:
diameter
Explanation:
You want the name for a line segment that passes through the center and has endpoints on the circumference of a circle.
Vocabulary
There are several vocabulary terms related to circles. Terms like "radius," "diameter," "circumference," and others, can refer to part of a drawing involving a circle, or they can refer to the measures of those parts.
It can be useful to become familiar with these terms, as you will encounter them often in your study of geometry.
Diameter
A line segment that passes through the center of a circle and has endpoints on the circumference of that circle is called a "diameter."
Radius
The line segment from the center to one of the endpoints of a diameter is called the "radius." It is half the length of the diameter. Any segment from the center to the circumference is a radius, whether the rest of the diameter is shown or not.