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: Surgery
[{'content': 'Which is the preferred gas for laparoscopy \nSelect and explain. \nA. CO2, B. N2O, C. O2, D. N2', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]