During Contraction of Skeletal Muscle Fibers, the

During contraction of skeletal muscle fibers, the

A) contractile proteins contract.
B) thin filaments slide inward toward the A band's center as a result of cycles of cross-bridge binding and bending.
C) thick and thin filaments become tightly coiled, thus shortening the sarcomere.
D) I bands slide in between the A bands.
E) lateral sacs of the sarcoplasmic reticulum shrink, pulling the Z lines closer together.