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
Which of the following metals shows the property of twinning: 
Select and explain. 
A. Stainless steel, B. Nickel-titanium alloy, C. Cobalt chromium, D. All of the above
B: Nickel-titanium alloy
Answer: B: Nickel-titanium alloy 
Explanation: None