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 rich materials include? 
Select and explain. 
A. Silicate cement, B. Glass ionomer cement, C. Polycarboxylate cement, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None