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: Radiology
[{'content': 'Hardener among the following is: \nSelect and explain. \nA. Sodium sulfite, B. Ammonium sulfite, C. Aluminium salts, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]