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': 'Irreversible injury in myocardium occurs at - \nSelect and explain. \nA. 2 minutes, B. 30 minutes, C. 2 hours, D. 5 hours', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans-Bo Myocardial function is more sensitive to ischemia(loss of contractility occurs within 60 seconds) than myocardial structure (irreversible injury occurs in 20-40 minutes, thus myocardial necrosis begins at approximately 30 minutes after coronary occlusion.FeatureTimeo Onset of ATP depletiono Loss of contractilityo ATP reduced to 50%o ATP reduced to 10%o Irrversible injuryo Microvascular injurySeconds< 2 minutes10 minutes40 minutes20-40 min> 1 hr', 'role': 'assistant'}]