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
Which among the following is used for sharpening of both stainless steel and carbon steel instrument: 
Select and explain. 
A. Arkansas., B. Silicon carbide., C. Alumina., D. Diamond.
D: Diamond.
Answer: D: Diamond. 
Explanation: None