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: Surgery
[{'content': 'Elgiloy is used in preparation of: \nSelect and explain. \nA. Vascular stent, B. Mesh, C. Bone plates, D. All of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: Self-expanding stents are deployed by retracting a restraining sheath. They usually consist of Elgiloy (a cobalt, chromium, nickel alloy) or nitinol (a shape memory alloy composed of nickel and titanium), the latter of which will contract and assume a heat-treated shape above a transition temperature that depends upon the composition of the alloy. Ref: Schwaz's principle of surgery 9th edition, chapter 23.", 'role': 'assistant'}]