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
Cleaning of base metal alloy is done by 
Select and explain. 
A. Warm HCl, B. Cold HF, C. Cold H2 So4, D. Sand blasting with aluminium oxide
D: Sand blasting with aluminium oxide
Answer: D: Sand blasting with aluminium oxide 
Explanation: None