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: Pathology
Most commonly submerged tooth is 
Select and explain. 
A. Mand. primary 1st molar, B. Mand. primary 2nd molar, C. Maxi. primary 1st molar, D. Maxi. primary 2nd molar
B: Mand. primary 2nd molar
Answer: B: Mand. primary 2nd molar 
Explanation: None