Answer: 2. Bending of the arm
Explanation: The second answer choice is the only on that involves use of both the skeletal and muscular system.
Someone already asked this question and someone else answered it so here's their answer.
Exercise programs and sports activities can differ in number of participants from one person doing an activity like jogging or swimming, to hundreds of participants at a track meet. Structure can be loose in solo exercises where you can set your own pace, or be very strict in most competitive sports. Competition varies from none to highly competitive, and can be on an individual or team level. More complex sports and activities can present a high skill level.
Never start a job without knowing the adress that its at and the type of chemicals you are working with
I researched and I believe the answer is both 2 and 4.