Each myosin head cross-bridge cycle uses energy derived from ________.
A. hydrolysis of the same number of ATPs as the number of light chains associated with the myosin neck region
B. hydrolysis of a variable number of ATPs depending on the size of the myosin step size
C. hydrolysis of a variable number of ATPs depending on the size of the cargo moved or the intensity of the signal for muscle contraction
D. hydrolysis of one ATP
E. hydrolysis of two ATPs