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': 'Length of blade in a no 10 and no 40 k file is respectively \nSelect and explain. \nA. 16 and 25, B. 25 and 16, C. 16 for both, D. 25 and 22', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]