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 of the following permanent tooth is least extracted for orthodontic treatment? 
Select and explain. 
A. Canines, B. Maxillary first permanent molar, C. 1st molar, D. 2nd molar
A: Canines
Answer: A: Canines 
Explanation: The teeth least commonly extracted is canine.