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': 'All are true about osseous crater except \nSelect and explain. \nA. 2/3rd of all mandibular defects, B. 2 times more common in anterior region as compared to posterior, C. 85% lingual and facial height is same, D. 1/3rd of all defects', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]