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
Anti-calculus agent in toothpaste is 
Select and explain. 
A. Cocoamidopropyl, B. Pyrophosphate, C. Fluoride, D. Lauryl sulphate
B: Pyrophosphate
Answer: B: Pyrophosphate 
Explanation: None