Answer: Release of acetylcholine from the synaptic vesicles
Explanation: Acetylcholine is a neurotransmitter of nerve impulses within the central and peripheral nervous systems. It is formed during the esterfication reaction between acetic acid and choline. After its formation, acetylcholine is transprted to a vesicle, where a transporter protein actively pumps the choline into the vesicle. Acetylcholine is stored until a need arises for it to be released.