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
Regular inspection of hand files may aid in avoidance of instrument separation. What file defects should be looked for on inspection? 
Select and explain. 
A. Unwinding of the flutes, B. Rolling up or tightening of the flutes, C. Distortion of the tip, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None