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 maximum rate of eruption, as the tooth cusps reach the surface epithelium is around ___________ μm/day. 
Select and explain. 
A. 100, B. 75, C. 50, D. 25
B: 75
Answer: B: 75 
Explanation: None