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
Which primary tooth has longest duration of function 
Select and explain. 
A. mandibular canine, B. maxillary canine, C. mandibular 2nd molar, D. maxillary 2nd molar
B: maxillary canine
Answer: B: maxillary canine 
Explanation: Maxillary Permanent canine has the longest duration of function and is last to shed off. One of the reasons is its long root.