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
Hedstroem file is an instrument used for 
Select and explain. 
A. Canal enlargement, B. Length determination, C. Obturating with gutta percha in McSpadden technique, D. Endodontic implants
A: Canal enlargement
Answer: A: Canal enlargement 
Explanation: None