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
The lingual bar connector should be located at least how many millimeters below the gingival margin? 
Select and explain. 
A. 2, B. 4, C. 6, D. 8
B: 4
Answer: B: 4 
Explanation: None