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
Coefficient of thermal expansion of amalgam is: 
Select and explain. 
A. 7.2a(ppm k-1)., B. 10.0(ppm k-1)., C. 25.0(ppm k-1)., D. 48.5(ppm k-1).
C: 25.0(ppm k-1).
Answer: C: 25.0(ppm k-1). 
Explanation: None