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': 'Difference between class II amalgam and cast restoration is \nSelect and explain. \nA. Bevels, B. Occlusal resistance form, C. Outline form, D. Proximal retention', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]