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 is added to drinking water in the form of: 
Select and explain. 
A. Hydroﬂuosilicic acid, B. Fluoride ions, C. APF, D. None of the above
A: Hydroﬂuosilicic acid
Answer: A: Hydroﬂuosilicic acid 
Explanation: Fluoride compounds used in water fluoridation

Fluorspar 
Sodium fluoride 
Silicofluoride 
Sodium silicofluoride 
Ammonium silicofluoride 
Hydrofluosilicic acid.

Essentials of preventive and community dentistry
Soben Peter page no. 268