The muscle fiber contracts by a sequence of events initiated by the acetylcholine. Which of the following is the correct sequence?
I-The calcium-troponin complex pulls away tropomyosin from the binding sites of actin.
II-The freed-sites of actin now can bind to myosin to form cross bridges.
III-Calcium ion binds to the troponin.

A. I, III, and II
B. III, II, and I
C. II, III, and I
D. I, II, and III
E. III, I, and II