Hi, Daniel and Ankur;
Answer 1 is absolutely wrong, it would have been right if it is phrased like this: an object will be eligible for gc (note that it is not guaranteed that it will be deleted)when they can be no longer referenced by any reference.
So, IMHO, 3, 5 would be correct, but I am not sure about 4, I will choose it.
Correct me if I am wrong.