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': 'Morphine causes vomiting by acting on- \nSelect and explain. \nA. C.T.Z, B. Gastric mucosa, C. Both of the above, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., C.T.Z", 'role': 'assistant'}]