Question

multiple choice question as tropomyosin shifts away from the myosin binding sites on actin, the myosin head can now form a temporary link with actin, called a cross - bridge myosin - actin bond power stroke

Explanation:

In muscle - contraction, when tropomyosin moves away from myosin - binding sites on actin, the myosin head forms a cross - bridge with actin. A myosin - actin bond is a more general term, and a power stroke is the movement that occurs after cross - bridge formation.

Answer:

A. cross - bridge