How does the muscular system humans maintain posture?
muscles continually align themselves vertically to maintain posture.
muscles continually push bones to be straight.
muscles constantly contract and relax to fight gravity.
muscles constantly contract and relax to work with gravity.

Answer;

Muscles constantly contract and relax to help fight gravity

Explanation;

-Muscles are the only tissue in the body that has the ability to contract and therefore move the other parts of the body.

-The main function of the muscular system is movement, but it also helps stabilize our joints, maintain our posture and generate heat during activity.

The answer is C- muscles constantly contract and relax to help fight gravity