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': 'Sodium lauryi sulphate used in the toothpaste is \nSelect and explain. \nA. Humectant, B. Abrasive, C. Flavouring agent, D. Surfactant', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]