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': 'Mechanically, the strongest phase in amalgam restoration is \nSelect and explain. \nA. The original gamma phase (Ag3Sn), B. The gamma I phase, C. The gamma II phase, D. The copper — Tin phase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]