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: Anaesthesia
[{'content': 'True regarding morphine – \nSelect and explain. \nA. Tolerance develops for all except miosis and constipation, B. Tolerance to all effects develops with chronic usage, C. Tolerance develops for all except euphoria and sedation, D. Tolerance can develop to all effects in high doses', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Tolerance is exhibited to most actions of morphine except for miosis and constipation.', 'role': 'assistant'}]