Problem: Choose the best statement that best describes the power stroke in the contraction of a muscle fiber according to the sluding filament theory. a) ADP on the actin is hydrolyzed, and the myosin slides past the actin. b) Filaments of actin reach out and pull the myosin filaments closer together. c) ADP+P on the myosin head are released and the myosin head bends, pulling the actin. d) ATP pulls back the myosin head, releasing it from actin.