Which of the following correctly states the relationship between the radius and diameter of a circle?

The relationship between the radius and diameter of a circle is defined by the fact that the diameter is twice the length of the radius. Therefore, it can be expressed mathematically in two equivalent forms: the first form states that the diameter equals two times the radius (Diameter = 2 × Radius), and the second form states that the diameter equals the radius multiplied by two (Diameter = Radius × 2). Both formulations convey the same concept, just worded differently.

Since both of the statements relating diameter to radius are correct, the option indicating that both A and B are correct accurately represents the established relationship. Understanding that the diameter is twice the radius helps reinforce the fundamental characteristics of circles, which is crucial in geometry and helps in various applications involving circles.