What is the length of a circle's diameter if the radius measures 7?

The diameter of a circle is twice the length of the radius. This relationship is based on the definition of the circle: the diameter is the line segment that passes through the center of the circle and connects two points on its boundary. When the radius is given as 7, you calculate the diameter by multiplying the radius by 2.

So, in this case, if the radius measures 7, the calculation would be:

Diameter = 2 × Radius = 2 × 7 = 14.

This means that the length of the diameter is 14, confirming the selection as the correct answer.