Insert the Missing Code in the Following Code Fragment

Multiple Choice

Insert the missing code in the following code fragment. This fragment is intended to create an iterator to be used to process elements of a tree. TreeSet<String> aTree = . . .
String first = iter.next() ;
String second = iter.next() ;

A) Iterator<String> iter = aTree.iterator<String>() ;
B) Iterator<String> iter = aTree.iterator() ;
C) Iterator<String> iter = String.iterator() ;
D) Iterator<TreeSet> iter = aTree.iterator() ;