According to the Sliding-Filament Model of Contraction, How Does Muscle

Multiple Choice

According to the sliding-filament model of contraction, how does muscle contraction occur?

A) The myosin heads propel the actin myofilaments toward the center of the sarcomere; this pulls the Z disks closer together, which shortens the sarcomere and the entire muscle.
B) The actin heads propel the myosin filaments toward the center of the sarcomere; this pulls the Z disks closer together, which shortens the sarcomere and the entire muscle.
C) The myosin heads propel the actin myofilaments toward the center of the sarcomere. This causes the myofilaments to shorten, which pulls the Z disks closer together to shorten the sarcomere and the entire muscle.
D) Both the actin and myosin myofilaments shorten, which shrinks the sarcomere and pulls the Z disks closer together. As the Z disks move closer together, the muscle contracts.