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 lingual bar connector should be located at least how many millimeters below the gingival margin? \nSelect and explain. \nA. 2, B. 4, C. 6, D. 8', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]