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': 'For highly visible gingiva, it is advisable to select \nSelect and explain. \nA. Conical teeth and short contact areas, B. Conical teeth and long contact areas, C. Square teeth and short contact point, D. None of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]