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': 'Myocardial oxygen demand depends upon- \nSelect and explain. \nA. Preload, B. Afterload, C. Intramyocardial tension, D. Blood Hb concentration', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Preload, B. Afterload, C. Intramyocardial tensionRef: Ganong, 25th ed/p.611Primary determinants of myocardial oxygen consumption are,#intramyocardial tension#contractile state of the myocardium#heart rate#Ventricular work (preload and afterload)-Ventricular work is the product of stroke and mean arterial pressure', 'role': 'assistant'}]