The Sliding Filament Model for Muscle Contraction Can Be Studied $\mu$

The sliding filament model for muscle contraction can be studied using an isolated skeletal muscle that is fixed at each end, while a machine records the tension that is generated when the muscle is stimulated to contract. In one particular muscle tested, the length of the thick filaments was 1.6 $\mu$ m and the length of the thin filaments that project in from each Z line towards the center of the sarcomere was 1.0 $\mu$ 0m. A summary of the results comparing sarcomere length to the degree of tension produced during contraction is shown below. What most likely explains the difference between segment II and segment III of the graph?

A) There is an increasing overlap of the free ends of the thin filaments in segment III but not in segment II.
B) Fewer myosin cross-bridges are forming in segment II than in segment III.
C) The length of the thick filaments is decreasing in segment III but not in segment II.
D) The distance between the Z lines is constant in segment II but rapidly increasing in segment III.
E) The muscle cells used up all the ATP by the end of segment II.
F) The length of the thin filaments is decreasing in segment III but not in segment II.