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
Retarder present in the composition of alginate is: 
Select and explain. 
A. Calcium sulphate, B. Sodium phosphate, C. Potassium sulphate, D. Calcium phosphate
B: Sodium phosphate
Answer: B: Sodium phosphate 
Explanation: Powder Composition for an Alginate Impression Material: