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
Water content in enamel by volume 
Select and explain. 
A. 2-3%, B. 6-7%, C. 20-25%, D. 10-12%
B: 6-7%
Answer: B: 6-7% 
Explanation: None