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
Water quenching a gold alloy casting (within its investment. is done immediately after the dull redness of the button disappears is done to: 
Select and explain. 
A. Increase the degree of ductility of the casting, B. Decrease corrosion, C. Facilitate the easy removal of the casting from its mold, D. To achieve a desirable surface on the casting
C: Facilitate the easy removal of the casting from its mold
Answer: C: Facilitate the easy removal of the casting from its mold 
Explanation: None