Which statement correctly identifies the diameter of a circle?

• A. A segment from the center to the edge.
• B. The distance around a circle.
• C. A point on the circle.
• D. A segment through the center that connects two points on the circle; equals 2r.

Answer: (D)

Diameter is a segment that passes through the circle’s center and has its endpoints on the circle. This means it stretches from one point on the circle to the opposite point, crossing the center. Since the distance from the center to a point on the circle is the radius, the diameter is twice that distance, so diameter equals 2r. A segment from the center to the edge is a radius, not a diameter. The distance around a circle is the circumference, not a segment. A single point on the circle isn’t a segment. The statement describing a segment through the center that connects two points on the circle and has length 2r is the correct one.