This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
Which one of the following sites is characterized by adrenergic neurohumoral transmission? 
Select and explain. 
A. Parasympathetic preganglionic fibers, B. Sympathetic postganglionic fibers, C. Sympathetic fibers in the adrenal medulla, D. Synaptic fibers in the ecrine gland
C: Sympathetic fibers in the adrenal medulla
Answer: C: Sympathetic fibers in the adrenal medulla 
Explanation: The term neurohumoral means "nerve-blood." The only site in the ANS where neurohumoral transmission occurs is the adrenal medulla, where sympathetic nerve activity elicits the release of catecholamines into the blood.