At What Point During Excitation Contraction Coupling Does Exocytosis Play

At what point during excitation contraction coupling does exocytosis play a role?

A) during calcium ion reuptake into the sarcoplasmic reticulum
B) when sodium channels open up on the motor end plate
C) during acetylcholine release from the synaptic terminal
D) when the action potential surges through the T-tubules
E) when ATP splits into ADP and P on the free myosin head