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
Co-efficient of Thermal expansion of amalgam is 
Select and explain. 
A. 6.6 a (ppm k-1), B. 11.4 a (ppm k-1), C. 14.0 a (ppm k-1), D. 25.0 a (ppm k-1)
D: 25.0 a (ppm k-1)
Answer: D: 25.0 a (ppm k-1) 
Explanation: None