This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'Which of the following is not true about 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 hea 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 hea disease is the most common cause of sudden death.', 'role': 'assistant'}]