Answer:
e. Because ATP is needed to break the cross bridge between actin and myosin
Explanation:
The energy for muscle contraction comes from ATP (adenosine triphosphate) molecules produced during cellular respiration. These molecules act on the binding of myosin to actin, causing muscle contraction.
ATP acts both on the binding of myosin to actin and on its separation, which occurs during muscle relaxation. When ATP is lacking, myosin stays attached to actin, causing muscle tightness. This is what happens after death, producing the state of rigor mortis.