If all of the image within a muscle fiber was removed, which of the following could still occur?

a. An action potential that was produced at the neuromuscular junction would be propagated along the sarcolemma.
b. The troponin molecules bound to G actin molecules would be released, causing tropomyosin to move.
c. The heads of the myosin molecules would return to their resting position, and the recovery stroke would occur.
d. The heads of the myosin myofilaments would bind to G-actin to form cross-bridges.