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
Amalgam achieves 70% of the strength by: 
Select and explain. 
A. 2 hours, B. 4 hours, C. 8 hours, D. 16 hours
C: 8 hours
Answer: C: 8 hours 
Explanation: None