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': 'Corrosion product of high copper amalgam \nSelect and explain. \nA. SnO, B. SnHg, C. Sn-O Cl, D. Cu-sn', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]