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
In air-abrasive technology the abrasive particles used are 
Select and explain. 
A. Iron oxide, B. Tin oxide, C. Aluminium oxide, D. Silicon oxide
C: Aluminium oxide
Answer: C: Aluminium oxide 
Explanation: None