In parasympathetic nervous system, which of the following is released?

Autonomic Nervous System (ANS) automatically regulates the activities of smooth muscles, cardiac muscles and glands. This coordination is involuntary. Autonomic nervous system consists of two divisions :(i) Sympathetic ANS : It shows sympathy, ie, generally increases the function and expenditure of energy takes place. Preganglionic nerve secretes acetylcholine and postganglionic nerve secrete "sympathatin" (norepinephrine). (ii) Parasympathetic ANS : It provides relaxation, comfort, pleasure at the time of rest and conservation of energy takes place. Postganglionic nerve secretes acetylcholine. Serotonin is a vasoconstrictor, secreted from mast cells.