Correct option: (a) Acetylcholine Acetylcholine
Explanation:
The autonomic nervous system is a division of the peripheral nervous system, which controls the involuntary responses of the glands and smooth muscles. The stomach is innervated by 2 classes of autonomic nerves: parasympathetic and sympathetic. The former stimulates the muscle while the latter inhibits it. Acetylcholine is released from the axon terminal, diffuses across the synaptic cleft and causes an action potential to be generated and spread to the next neuron. Acetylcholine is again released at the nerve ending Y to trigger all the acetylcholine receptors in the muscle.
