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': 'Ejection fraction is about \nSelect and explain. \nA. 25%, B. 45%, C. 55%, D. 65%', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The ejection fraction, the percent of the end-diastolic ventricular volume that is ejected with each stroke, is about 65%. The ejection fraction is a valuable index of ventricular function.', 'role': 'assistant'}]