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': 'All of the following are methods for improving oxygenation using a ventilator, except: \nSelect and explain. \nA. High frequency ventilation, B. Low tidal volume high PEEP, C. Extracorporeal membrane oxygenation (ECMO), D. Prone ventilation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. High frequency ventilation', 'role': 'assistant'}]