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
Mercuroscopic expansion in dental amalgam occurs when: 
Select and explain. 
A. Moisture contamination occurs during condensation of zinc containing amalgam, B. Moisture contamination occurs during trituration of zinc containing amalgam, C. Mercury released as a result of electrochemical corrosion re-reacts with Ag-Sn particle, D. Mercury released as a result of electrochemical corrosion re-reacts with Ag-Cu particle
C: Mercury released as a result of electrochemical corrosion re-reacts with Ag-Sn particle
Answer: C: Mercury released as a result of electrochemical corrosion re-reacts with Ag-Sn particle 
Explanation: None