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
Tip diameter of a no. 245 bur is ______mm 
Select and explain. 
A. 0.8, B. 1.2, C. 1, D. 1.5
A: 0.8
Answer: A: 0.8 
Explanation: It is inverted cone shape with diameter .8mm and length 3mm.