This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
____________ is an example for rapidly acting
neurotransmitter 
Select and explain. 
A. Somatostatin, B. Calcitonin, C. Substance P, D. Glycine
D: Glycine
Answer: D: Glycine 
Explanation: None