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': 'Opioid tolerance develops to all of the following actions, except: \nSelect and explain. \nA. Miosis, B. Analgesia, C. Euphoria, D. Nausea and vomiting', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Wasis Tolerance is exhibited to most actions of morphine except for miosis and constipation.", 'role': 'assistant'}]