What geometric figure is defined as a locus of points?

A locus of points refers to a collection of all points that satisfy a particular condition or set of conditions defined in geometry. In the context of the options provided, a circle is defined as the locus of all points that are equidistant from a central point. This central point is known as the center of the circle, and the constant distance from this center to any point on the circle is referred to as the radius.

For example, if you were to take a point on a piece of paper, then measure a fixed distance (the radius) in all directions, you would trace out a circle. This unique relationship between all points on the circumference and the center illustrates how a circle perfectly fits the definition of a locus of points.

In contrast, a triangle, a line, and a square do not inherently fulfill the same definition as they do not describe a set of points based on a uniform distance from a center point or fulfill a single condition in the same manner that circles do. While they are indeed geometric figures made up of specific points, they do not represent a locus in the way defined here.