Which Step Is Not Part of the Sequence of Events

Multiple Choice

Which step is not part of the sequence of events that triggers synaptic transmission from a neuron to a muscle fiber?

A) Entry of Ca²⁺ into the presynaptic terminal
B) Release of norepinephrine into the synaptic cleft
C) Opening of Ca²⁺ channels in the presynaptic terminal
D) Arrival of an action potential at the presynaptic terminal
E) Fusion of synaptic vesicles with the presynaptic membrane