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
[{'content': 'Retarder present in the composition of alginate is: \nSelect and explain. \nA. Calcium sulphate, B. Sodium phosphate, C. Potassium sulphate, D. Calcium phosphate', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Powder Composition for an Alginate Impression Material:', 'role': 'assistant'}]