I'm pretty sure the answer to this question is choice D.
Answer:
Muscular contractions are the mechanism that allow an individual, animal, or human, to move its body, move the food in its digestive system, or a host of other activities. The contraction shortens the muscle which moves the rigid structures, bones, to which they are attached.
Explanation:
I believe the muscle contracts
The answer is b . It can help improve the poor posture responsible for back pain
