This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'Cardiac output in L/min divided by heart rate equals \nSelect and explain. \nA. Cardiac efficiency, B. Mean stroke volume, C. Cardiac index, D. Mean arterial pressure', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Mean stroke volumeRef: Ganong, 25th ed/p.544Cardiac output is the product of heart rate (HR) and stroke volume (SV)So, Cardiac output/heart rate = stroke volume', 'role': 'assistant'}]