This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Which of the following factor is determined by preload? \nSelect and explain. \nA. End systolic volume, B. End diastolic volume, C. Peripheral resistance, D. Stroke volume', 'role': 'user'}, {'content': "Answer: B \nExplanation: Preload is the initial stretching of the cardiac myocytes prior to contraction; therefore, it is related to the sarcomere length at the end of diastole. Sarcomere length cannot be determined in the intact hea so indirect indices of preload, such as ventricular end-diastolic volume or pressure, must be used. Ref: Cardiovascular Physiology Concepts By Richard E. Klabunde, 2005, Page 69; Guyton's physiology 22nd edition, Page 111.", 'role': 'assistant'}]