What nerve endings liberate acetylcholine?

The correct answer is cholinergic. Cholinergic nerve endings are responsible for the release of acetylcholine, which is a crucial neurotransmitter in both the central and peripheral nervous systems. Acetylcholine plays a significant role in muscle contraction at the neuromuscular junction and is also involved in various autonomic functions, including heart rate and digestion.

In the context of the other options, adrenergic nerve endings are associated with the release of norepinephrine and are primarily involved in the body's fight-or-flight responses. Serotonergic refers to the nerve endings that release serotonin, which is primarily involved in mood regulation and various other physiological functions. Dopaminergic nerve endings release dopamine, a neurotransmitter important for motivation, pleasure, and motor control. Each of these types of nerve endings plays a distinct role in neurotransmission, making cholinergic the only one that specifically liberates acetylcholine.