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': 'What will not help in reducing discoloration of amalgam restored tooth? \nSelect and explain. \nA. Well condensation, B. Void in restoration, C. Use of varnish on the walls prior to insertion of amalgam, D. Use of varnish over the restoration', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]