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
Volume determining preload is 
Select and explain. 
A. End diastolic volume of ventricles, B. End systolic volume, C. Volume of blood in aorta, D. Ventricular ejection volume
A: End diastolic volume of ventricles
Answer: A: End diastolic volume of ventricles 
Explanation: Ans. (a) End diastolic volume of ventriclesRef: Ganong, 25th ed/p.544Preload is End diastolic volume of ventriclesAfterload is the aortic pressure