This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiac Output, Subject name: Physiology
[{'content': 'Normal cardiac index in an adult is \nSelect and explain. \nA. 5.9 L/min/m2, B. 2.3 L/min/m2, C. 3.2 L/min/m2, D. 4.6 L/min/m2', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cardiac index: - Cardiac output per square meter of body surface area. i.e. Cardiac index = Cardiac output/Body surface area Experiments have shown that the cardiac output increases approximately in propoion to the surface area of body. The average human being who weighs 70 kilograms has a body surface area of about 1.7square meters, which means that the normal average cardiac index for adults is about 3 L / min/ M2 of body surface area.', 'role': 'assistant'}]