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: Psychiatry
[{'content': 'Withdrawal of which of the following causes piloerecton? \nSelect and explain. \nA. Morphine, B. Cannabis, C. Smoking, D. Alcohol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. MorphineManifestations of morphine withdrawalLacrimationAnxiety & fearSweatingRestlessness rYawningGooseflash (Piloerection).', 'role': 'assistant'}]