Which of the following terms describes the straightening of a joint, rather than the bending?
a. flexion
b. hyperextension
c. extension
d. none of the above

The answer is C. Extension

Extension is a movement that increased the angle of a joint, causing it to extend.

For example,if you do a bicep curls, you will lift the weight and form a 90 degree angle with your elbow, then straighten your arm and forming a 180 degree angle, you will technically straighten your joint while doing this kind of workout