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
Tannic acid acts as: 
Select and explain. 
A. Astringent, B. Keratolytic, C. Demulscent, D. Antiseptic
A: Astringent
Answer: A: Astringent 
Explanation: None