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
Silicoflouoride is used in: 
Select and explain. 
A. Dry feeder system., B. Saturator system., C. Solution feeder system., D. All of the above.
A: Dry feeder system.
Answer: A: Dry feeder system. 
Explanation: None