1:Myosin ATPase, 2:excitation-contraction coupling, 3:calcium, 4:depolarization, 5: acetylcholine, 6: creatine kinase, 7: excitation, 8: troponin, 9: actin, 10: epinephrine, 11: sarcolemma, 12: muscle shortening, 13: myosin, 14 sodium The process of begins with the and subsequent of a motor nerve. Afterwards, is released form the motor endplate and the muscle membrane depolarizes. is released and binds to resulting in the exposure of binding sites. The head binds and splits ATP to ADP and inorganic phosphate. The final outcome is .

The process of excitation-contraction coupling begins with the depolarization and subsequent excitation of a motor nerve. Afterwards, acetylcholine is released from the motor endplate and the muscle sarcolemma membrane depolarizes. Calcium is released and binds to troponin resulting in the exposure of actin binding sites. The myosin head binds and Myosin ATPase splits ATP to ADP and inorganic phosphate. The final outcome is muscle shortening.

Explanation:

The paragraph above summarizes the process of muscle contraction, which happens thanks to the release of acetylcholine in the neuromuscular junction, after the neuron is depolarized. The presence of acetylcholine will ultimately lead to the release of stored calcium so it can bind to a protein in the sarcomere called troponin. The binding of calcium and troponin will expose actin binding sites, making the binding of actin and myosin possible. The ATPase found in the myosin head will make use of ATP to produce the movement of myosin - this is how muscle contraction happens.

i think its both a and b