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
In a high copper amalgam, the phase which is eliminated is: 
Select and explain. 
A. Gamma 1, B. Gamma 2, C. Gamma 1 and 2, D. No phase is eliminated
B: Gamma 2
Answer: B: Gamma 2 
Explanation: A reaction between Cu3 Sn (ε phase) and γ2 occurs and yields Cu6Sn5  (η phase). Because of the low copper content, a majority of γ2 remains. The addition of more than 6% of copper by weight can reduce or eliminate the γ2 phase by the formation of Cu-Sn phase.
Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 344