Final answer:
The primary neurotransmitter of the parasympathetic nervous system is acetylcholine (ACh), which binds at motor end-plates to trigger depolarization, distinguishing it from the sympathetic nervous system which primarily uses norepinephrine. The correct option is B.
Step-by-step explanation:
The primary neurotransmitter of the parasympathetic nervous system is acetylcholine (ACh). Acetylcholine is responsible for triggering depolarization at motor end-plates. The sympathetic nervous system, in contrast, primarily uses norepinephrine as its neurotransmitter, with the exception of some postganglionic fibers that release acetylcholine at sweat glands.
In scenarios where the body experiences a rush of adrenaline, such as during the fight-or-flight response, the adrenal medulla releases epinephrine and norepinephrine into the bloodstream as hormones, not as neurotransmitters at synapses.
Therefore, options A) epinephrine, C) reteplase, and D) dopamine are incorrect answers to the question about the primary neurotransmitter of the parasympathetic nervous system.