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
D2 on the endodontic file indicates: 
Select and explain. 
A. Diameter at tip of instrument, B. Angle of instrument, C. Length of instrument, D. 1/100th mm at end of cutting blade
D: 1/100th mm at end of cutting blade
Answer: D: 1/100th mm at end of cutting blade 
Explanation: None