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
Fluoride incorporation during dentinogenesis 
Select and explain. 
A. Increase hardness of Dentin, B. Increase softness of dentin, C. No effect on hardness of dentin, D. None of the above
A: Increase hardness of Dentin
Answer: A: Increase hardness of Dentin 
Explanation: None