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': "During rapid sequence induction of anaesthesia: \nSelect and explain. \nA. Sellick's maneuver is not required, B. Pre-oxygenation is mandatory, C. Suxamethonium is contraindicated, D. Patient is mechanically ventilated before endotracheal intubation", 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Preoxygenation is mandatory', 'role': 'assistant'}]