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 shortest root on a maxillary first molar is: 
Select and explain. 
A. Mesio-buccal, B. Disto-buccal, C. Lingual, D. All are of equal length
B: Disto-buccal
Answer: B: Disto-buccal 
Explanation: None