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: Pharmacology
[{'content': 'Astringents are substances that : \nSelect and explain. \nA. Irritate sensory nerve endings, B. Precipitate proteins, C. Penetrate target cell nucleus for their action, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]