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': 'The plane of the axial wall of an M.O. cavity prepared for silver amalgam should be \nSelect and explain. \nA. A flat straight plane bucolingually, B. Parallel to the long axis of the teeth, C. Concave to allow greater bulk of amalgam, D. Parallel to the long axis of the teeth and should follow the buccolingual contour of the tooth', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]