Skeletal muscle produces body movement as well as maintains our as we sit.

Skeletal muscles produce body movements as well as maintain our posture as we sit. The skeletal muscles are responsible for producing movements of the body. Without the skeletal muscles, our bodies will seem amoeba-like which have no form and are gelatinous in nature. Aside from this, the skeletal muscles are responsible for providing support for the body, like the way we maintain our seated position. These muscles give cushioning to the bones and the internal organs. The skeletal muscles make-up most of the body’s tissues and play important roles in our everyday functions. 

Your answer is  d.)relationship between pressure and air volume and led to the understanding of how respiration works

True, using a pedometer can promote a physically active lifestyle.