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': 'Pulse oximeter is used for monitoring – \nSelect and explain. \nA. Oxygen content of blood, B. Oxygen saturation, C. Partial pressure of oxygen, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]