Answer:
B. ACh
Step-by-step explanation:
ACh or acetylcholine is the neurotransmitter, which is found in the sympathetic and parasympathetic neurons in the nervous system. Acetylcholine is kept or stored in vesicles at the ends of cholinergic neurons. It serves both as excitatory as well as inhibitory functions, which indicates that ACh can slow down or speed up nerve signals. It plays an important role in memory, arousal, neuroplasticity and, learning.