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 highest critical surface tension is for which of the orthodontic brackets? 
Select and explain. 
A. Stainless steel, B. Polycarbonate, C. Ceramic alumina, D. Titanium
A: Stainless steel
Answer: A: Stainless steel 
Explanation: None