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: Surgery
[{'content': 'Very commonly used suture material in oral surgical procedures \nSelect and explain. \nA. Chromic gut, B. Polygalactin, C. Cotton, D. Black silk', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]