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
For retraction of maxillary anteriors by 1 mm, space required is? 
Select and explain. 
A. 1 mm, B. 2 mm, C. 0.5 mm, D. 1.5 mm
B: 2 mm
Answer: B: 2 mm 
Explanation: For every 1 mm of decrowding, same amount required for alignment. 
For every 1 mm of leveling the curve of spee, 0.5 mm space required in the arch. 
For every 1 mm of incisor retraction, 2 mm space required.