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: Medicine
[{'content': 'All of the following arteries are common sites of occlusion by a except - \nSelect and explain. \nA. Left anterior descending, B. Right coronary artery, C. Circumflex coronary artery, D. Marginal artery', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]