The line segment that connects the center of a circle to any point on its circumference is called a radius.

The line segment that connects the centre to a point on the circle is called the Radius.

Explanation:
A circle is a closed figure in which all points on the circumference are equidistant from the center. The center of the circle is the point from which all other points on the circle are equidistant.

What is a Radius?
- The radius of a circle is the line segment that connects the center of the circle to any point on the circumference.
- It is the distance between the center and any point on the circle.

Characteristics of a Radius:
- The radius is always half the length of the diameter.
- All radii of a circle are equal in length.
- The radius is a straight line segment.

Importance of the Radius:
- The radius is a fundamental element of a circle and is used in various calculations and formulas related to circles.
- The length of the radius is crucial in determining the size, area, and circumference of a circle.
- It helps in measuring and locating points on the circumference of a circle.

Difference between Radius and Diameter:
- The diameter is a line segment that passes through the center and connects two points on the circumference, while the radius connects only one point on the circumference to the center.
- The diameter is always twice the length of the radius.

Why is the correct answer 'A'?
- The correct answer is option 'A', which is "Radius," because the radius specifically refers to the line segment that connects the center to a point on the circle.
- The diameter (option 'B') is a different line segment that passes through the center and connects two points on the circumference.
- The center (option 'C') is the point from which all radii originate, but it is not the line segment itself.
- Therefore, the line segment that connects the center to a point on the circle is called the Radius.