The schematic diagram is depicting some features of autonomic and somatic nervous systems. The neurotransmitter at site 'F' is
Acetylcholine (ACh) is the primary transmitter at ANS ganglia and at the somatic neuromuscular junction .Katzung Pharmacology 12th edition Pg: 80
Acetylcholine
Norepinephrine
Dopamine
Epinephrine
Autonomic nervous system