This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anesthesia Machine, Subject name: Anaesthesia
[{'content': 'Colour coding of halothane , isoflurane, sevoflurane and desflurane is respectively \nSelect and explain. \nA. red, purple, blue , yellow, B. red , purple, yellow , blue, C. red , yellow, purple, blue, D. red, blue , purple, yellow', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]