In this question, the term that describes the straightening of a joint, rather than the bending, is "extension." Extension is the movement that increases the angle between two body parts at a joint.
For example, when you straighten your arm from a bent position, you are performing extension at the elbow joint. Similarly, when you stand up straight from a forward-bending position, your spine undergoes extension.
So, in the context of joint movement, extension refers to the straightening of a joint, which is the opposite of flexion, which is bending at a joint. Hyperextension, on the other hand, refers to excessive extension beyond the normal range of motion.
Therefore, the correct answer to the question is option C: extension.
