Which two factors primarily influence flexibility?

The correct choice highlights the fundamental elements that directly impact flexibility: joint structure and muscle elasticity.

Joint structure refers to the anatomical configuration of the joints in the body, such as the type of joint (e.g., hinge, ball-and-socket) and the way the bones articulate with each other. The design of a joint can significantly affect the range of motion and, consequently, flexibility. For instance, some joints are more mobile than others due to their structural characteristics, enabling a greater degree of movement.

Muscle elasticity relates to the ability of muscle fibers to stretch and return to their original length. This elasticity is essential for maintaining flexibility because muscles need to lengthen adequately during stretches and activities involving a range of motion. Factors such as muscle temperature, hydration, and the properties of the muscle tissue itself can affect muscle elasticity.

Together, these factors are critical in determining an individual’s overall flexibility, making the option that includes joint structure and muscle elasticity the most relevant choice.