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': 'In venturi mask maximum O2 concentration attained is \nSelect and explain. \nA. 90%, B. 100%, C. 60%, D. 80%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Maximum concentration delivered by ventimask (venturimask) is 60%.', 'role': 'assistant'}]