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: Social & Preventive Medicine
Defluoridation of water is carried out using: 
Select and explain. 
A. Chlorine, B. Phosphate, C. Calcium, D. Ozone
B: Phosphate
Answer: B: Phosphate 
Explanation: Some areas may contain excessive fluoride levels in drinking water. Defluoridation is carried out using phosphates. Ref: Park 21st edition page: 672.