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
The term ordered hardening heat treatment used in which of the following dental alloys? 
Select and explain. 
A. Gold-Copper, B. Nickel-Chromium, C. Nickel-Titanium, D. Silver-Palladium
A: Gold-Copper
Answer: A: Gold-Copper 
Explanation: None