Question

which figure shows a radius?

Explanation:

A radius is a line segment that connects the center of a circle to any point on its circumference. The first and third figures show diameters (segments across the circle through the center, connecting two circumference points). The second figure only shows the center and circle, no segment. The fourth figure has a segment from the center to the circumference, fitting the radius definition.

Answer:

The fourth figure (rightmost, with a line from the circle's center to its edge)