Given:<br /> <img src="https://nimg.ppkao.com/2018-08/wenxueying/2018080114582225391.png?sign=39548ae86c3fc85c92e0c1cd12d9d462&t=62d4d4a2" /><br /> Which code, inserted at line 4, guarantees that this program will output [1, 2]?()
A、Set set = new TreeSet();
B、Set set = new HashSet();
C、Set set = new SortedSet();
D、List set = new SortedList();