This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
[{'content': 'Which coronary artery is occluded? \nSelect and explain. \nA. Left anterior descending, B. Left circumflex, C. Left diagonal branch, D. Left main stem', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer D. Left main stemThe 12-lead electrocardiogram shows ST-segment elevation in leads V1, V2, V3, I, aVL, and aVR and ST-segment depression in leads V4, V5, V6, II, III, and aVF, findings suggestive of occlusion of the left main stem of the coronary artery. The patient recovered following revascularization.', 'role': 'assistant'}]