Which of the following statements is INCORRECT?

• A. Skeletal muscle contractions help maintain body temperature.
• B. Skeletal muscles are responsible for the pumping action of the heart.
• C. Smooth muscles form valves regulating the passage of substances through internal openings of the digestive and urinary tracts.
• D. The contractions of skeletal muscles pull on tendons and move elements of the skeleton.
• E. Skeletal muscles support the weight of some internal organs.