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: Dental
[{'content': 'Which number blade is useful for Crevicular incision : \nSelect and explain. \nA. 10, B. 11, C. 12, D. 15', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Crevicular incision is also known as Second incision for which 12 number blade is used.', 'role': 'assistant'}]