When a muscle contraction occurs Select one a. the actin gets shorter b. the myosin gets shorter c. the Z-lines are pulled closer together d. both a and b?

The correct answer is c. the Z-lines are pulled closer together. During a muscle contraction, the actin and myosin filaments slide past each other, which shortens the sarcomere, the basic unit of muscle fiber, but neither filament actually gets shorter. Instead, the actin filaments are pulled toward the center of the sarcomere, bringing the Z-lines closer together.