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: Unknown
[{'content': 'Which is not true of cardiopulmonary resuscitation (CPR)? \nSelect and explain. \nA. Closed chest massage is as effective as open chest massage., B. The success rate for out-of-hospital resuscitation may be as high as 30% to 60%., C. The most common cause of sudden death is ischemic heart disease., D. Standard chest massage generally provides less than 15% of normal coronary and cerebral blood flow.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Closed chest massage is not as effective as open-chest massage in normalizing blood pressure or perfusion of vital organs, and closed chest massage does generally deliver 5% to 15% of normal coronary and cerebral blood flow. The success rate for out-of-hospital resuscitation has been as high as 30% to 60% when communities are prepared to institute CPR early after a cardiac arrest. Ischemic heart disease is the most common cause of sudden death.', 'role': 'assistant'}]