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
During rapid sequence induction of anaesthesia: 
Select and explain. 
A. Sellick's maneuver is not required, B. Pre-oxygenation is mandatory, C. Suxamethonium is contraindicated, D. Patient is mechanically ventilated before endotracheal intubation
B: Pre-oxygenation is mandatory
Answer: B: Pre-oxygenation is mandatory 
Explanation: B i.e. Preoxygenation is mandatory