Answer: C. 3 +2+5 +1 +4
Step-by-step explanation:
An action potential depolarizes the membrane of the presynaptic axon terminal.
Calcium ions rush into the neuron's cytoplasm.
The synaptic vesicles release a supply of neurotransmitter into the synaptic cleft.
Neurotransmitter binds with receptors associated with the postsynaptic membrane.
The ligand-gated ion channels open.