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': 'Which of the following is not found in commercially \navailable tooth paste? \nSelect and explain. \nA. Humectants, B. sweetening agents, C. detergents, D. astringent', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]