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: Pharmacology
[{'content': 'Which of the following does not exert an analgesic effect? \nSelect and explain. \nA. Cholinergic antagonists, B. Adrenergic antagonists, C. Morphine, D. Substance P antagonists', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]