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': 'Which of the following weakest phase of the set amalgam: \nSelect and explain. \nA. Beta-2, B. Gamma, C. Gamma-1, D. Gamma-2', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]