Which of the following is true in a skeletal muscle?
A. Movement of the cross-bridge occurs only when the myosin head is detached from the actin molecule.
B. The binding of ATP to actin causes detachment of the myosin head from the actin molecule.
C. The head of a myosin molecule is activated (energized) during the hydrolysis of GTP (which is bound to the myosin head) to GDP and Pi.