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': 'Semiclosed circuit system \nSelect and explain. \nA. Needs advanced monitoring, B. Complex, C. More environmental pollution, D. More economical', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Semiclose breathing circuit is less economical, causes more environmental pollution. It is simple portable and no need of advanced monitoring.', 'role': 'assistant'}]