This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Inhalational Anesthetic Agents, Subject name: Anaesthesia
[{'content': 'Minimal mandatory Percentage of oxygen used in general anaesthesia is \nSelect and explain. \nA. 33%, B. 30%, C. 21%, D. 66%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: minimum mandatory is 30% oxygen. Less than 30 % can only is allowed in surgeries with high risk of fire hazard. There we decrease oxygen under strict monitoring.', 'role': 'assistant'}]