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
Astringents are substances that : 
Select and explain. 
A. Irritate sensory nerve endings, B. Precipitate proteins, C. Penetrate target cell nucleus for their action, D. All of the above
B: Precipitate proteins
Answer: B: Precipitate proteins 
Explanation: None