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 largest mesiodistal diameter in primary dentition is: 
Select and explain. 
A. Mandibular 1st molar, B. Mandibular 2nd molar, C. Maxillary 2nd molar, D. None of the above
B: Mandibular 2nd molar
Answer: B: Mandibular 2nd molar 
Explanation: None