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
Myocardial oxygen demand depends upon- 
Select and explain. 
A. Preload, B. Afterload, C. Intramyocardial tension, D. Blood Hb concentration
A: Preload
Answer: A: Preload 
Explanation: 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