What happens as a result of ion flow at a presynaptic terminal?

synaptic vesicles migrate to the plasma membrane and release acetylcholine.
acetylcholine is passively transported from the presynaptic neuron.
acetylcholine is actively transported to the postsynaptic neuron.
ligand-gated sodium channels open.
sodium ions diffuse into the cell.

The correct answer is: Synaptic vesicles migrate to the plasma membrane and release acetylcholine.

Action potential travels through the membrane of the presynaptic cell causing the channels permeable to calcium ions to open. Ca2+ flow through the presynaptic membrane and increase the Ca concentration in the cell which will activate proteins attached to vesicles that contain a neurotransmitter (e.g. acetylcholine), Vesicles fuse with the membrane of the presynaptic cell, thereby release their contents into the synaptic cleft-space between the membranes of the pre- and postsynaptic cells.

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