What is the term used for the straightening of a body part or joint?

The term that describes the straightening of a body part or joint is "extension." When a joint is extended, the angle between the bones increases, restoring the body part to its anatomical position after being flexed. This movement is essential in various activities, as it allows for increased range of motion and contributes to overall mobility. For example, when you straighten your elbow after bending it, you are performing an extension movement.

Other terms in the choices refer to different types of movements: flexion involves bending a body part, adduction refers to moving a body part toward the midline of the body, and rotation denotes the circular movement around an axis. Understanding these definitions clarifies why extension is the correct term for straightening a joint or body part.