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': 'A 25 year old male is undergoing incision and drainage of abscess under general anaesthesia with spontaneous respiration. The most efficient anaesthetic circuit is – \nSelect and explain. \nA. Maplelson A, B. Mapleson B, C. Mapleson C, D. Mapleson D', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]