Skeletal muscle support and Movement. Skeletal muscles move the body. Skeletal muscle contractions pull on tendons, which are attached to bones. If contraction of the muscle causes the muscle to shorten, the bone and, thus, the body part will move.
so your answer is D
Keep in mind that when speaking of muscle (I'm assuming in a mammal) there are three types:
skeletal muscle smooth muscle cardiac muscle
skeletal muscle is under voluntary control, smooth muscle in under autonomic control, and cardiac muscle is under the control of the pace-maker cells of the sinoatrial (SA) or the atrioventricular (AV) node
So, marching down through these:
A) moves food and substances through the GI tract - this would be SMOOTH muscle
B) helps maintain body posture - this would be SKELETAL muscle
C) promotes the flow of lymph - tricky... this would also be the SKELETAL muscles: contraction of skeletal muscles "squeezes" the fluid in the lymphatics, which ultimately drain into the venous system
D) moves the bones of the skeleton: this would be SKELETAL muscle
E: helps to adjust blood vessel diameter: this would be SMOOTH muscle
