Answer: It is a segment from a point on the circle to the center of the circle.
Explanation:
We know that the diameter is a line segment which start from one point on circle to end another point on circle which passes through the center of circle.
The radius is half the length of diameter of circle.
It is a line segment which starts from center to any point on the circle.
Hence, It is a segment from a point on the circle to the center of the circle.