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
Nickel is added to wrought gold alloys as 
Select and explain. 
A. Strengthener, B. Hardener, C. Whitens the alloy, D. Scavenger
A: Strengthener
Answer: A: Strengthener 
Explanation: None