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': 'Silk is which class of suture? \nSelect and explain. \nA. 1, B. 2, C. 3, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: United States of pharmacopeia classification of suture\nClass 1...silk\nClass 2...cotton\nClass 3...metal suture', 'role': 'assistant'}]