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: Pathology
[{'content': "In frey's syndrome, neurotransmitter is: \nSelect and explain. \nA. Acetylcholine., B. Epinephrine., C. Norepinephrine., D. Serotonin.", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]