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 cavosurface angle formed in cast metal restorations is \nSelect and explain. \nA. 90 degree; Butt joint, B. 130-140 degree; Lap sliding fit, C. 130-140 degree; Butt joint, D. 90 degree; Lap sliding fit', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]