A) 50%
B) 60%
C) 70%
D) 80%
E) 90%

A) A bands
B) H bands
C) I bands
D) sarcoplasmic reticulum
E) Z lines

A) participate in the propagation of an action potential along the surface of the muscle fiber.
B) bind troponin, which in turn permits tropomyosin to uncover the cross-bridge binding site on the thin filament.
C) bind tropomyosin, which in turn permits troponin to uncover the cross-bridge binding site on the thin filament.
D) activate a calcium-calmodulin-dependent protein kinase, which in turn phosphorylates and activates myosin.