Final answer:
The major neurotransmitter released from autonomic sympathetic postganglionic nerve terminals is Norepinephrine, which acts by binding to adrenergic receptors.
Step-by-step explanation:
The major transmitter released from autonomic sympathetic postganglionic nerve terminals is B) Norepinephrine. This neurotransmitter binds to adrenergic receptors on the target cell. While all preganglionic fibers of both the sympathetic and parasympathetic nervous systems release Acetylcholine (ACh), it is the postganglionic fibers of the sympathetic nervous system that predominantly release norepinephrine. However, postganglionic sympathetic fibers that project to sweat glands and a few blood vessels involved with skeletal muscles release ACh.
Norepinephrine acts as a neurotransmitter when it is released from postganglionic sympathetic axons, while it is considered a hormone when released into the bloodstream, such as from the adrenal medulla. The signaling molecules released by the autonomic system can bind to various receptors such as muscarinic receptors, which are G protein-coupled receptors, and nicotinic receptors, which are ligand-gated ion channels responsible for depolarization of the postsynaptic membrane in ganglionic neurons.