Question about Sun's sample questions

[Tom Tang]

8. Which two statements are true for the class java.util.TreeSet? (Choose two.)
A.The elements in the collection are ordered.
B.The collection is guaranteed to be immutable.
C.The elements in the collection are guaranteed to be unique.
D.The elements in the collection are accessed using a unique key.
E.The elements in the collection are guaranteed to be synchronized
The answer is A and C. I have a question regarding A. I know TreeSet is sorted, but is sorted the same as ordered? I originally thought only List implementations are ordered.

[natarajan meghanathan]

The question is on TreeSet and they have referred it as collection (quite misleading but have to be careful).
So the elements in a treeset are ordered and unique (inherited from sets). there is no key concept in treeset.