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': 'In facial porcelain margin, the risk of fracture can be reduced by \nSelect and explain. \nA. Increased axial depth upto 3 mm, B. Cavosurface margin at 90 degree, C. Margins of the tooth reduction at incisal edge, D. Providing contact during centric relationship', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]