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
Shape memory in NiTi is because of stress induced form 
Select and explain. 
A. Austenite to martensite, B. Martensite to austenite, C. Ferrite to austenite, D. Austenite to ferrite
A: Austenite to martensite
Answer: A: Austenite to martensite 
Explanation: None