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 about mapleson D circuit is \nSelect and explain. \nA. FGF for spontaneous ventilation is equal to minute ventilation, B. Expiratory valve is closer to patient, C. 1.8 times the minute ventilation is required gas flow for controlled ventilation., D. Preferred circuit for spontaneous ventilation.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Expiratory valve is away from the patient end in mapleson D circuit. 3 times minute ventilation is required for spontaneous ventilation.\nMapleson A is the preferred circuit for spontaneous ventilation.', 'role': 'assistant'}]