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: Physiology
[{'content': 'Cardiac index in a normal person is \nSelect and explain. \nA. 2.1, B. 3.2, C. 4.6, D. 5.9', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]