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': 'Which one of the following device provides fixed performance oxygen therapy: \nSelect and explain. \nA. Nasal Cannula, B. Venturi mask, C. O2 by T-piece, D. SO2', 'role': 'user'}, {'content': "Answer: B \nExplanation: B i.e. Ventimask Ventimask or venturimasks are high flow or fixed performance (performance not affected by changes in patient's tidal volume and respiratory rate) oxygen delivery devicesQ delivering accurate oxygen concentration", 'role': 'assistant'}]