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
[{'content': 'In air-abrasive technology the abrasive particles used are \nSelect and explain. \nA. Iron oxide, B. Tin oxide, C. Aluminium oxide, D. Silicon oxide', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]