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
How soon after a moisture contamination does a zinc containing amalgam alloy start expanding: 
Select and explain. 
A. 24 hours, B. 1-2 days, C. 3-5 days, D. 7 days
C: 3-5 days
Answer: C: 3-5 days 
Explanation: None