How many eligible for GC?

[Anuradha Prasanna]

This is a question from ExamLab. How many objects are eligible for GC?

Class A{
A aob;

public static void main(String[] args){

A a = new A();
A b = new A();
A c = new A();

a.aob = b;
b.aob = a;
c.aob = a.aob;

A d = new A().aob=new A();  // line-1
c=b;
c.aob = null;
System.gc();
}
}

Answer is 2.

But i think, only 1 is eligible for GC ie. the object refered to by c before it is nulled.
Is there any object eligible for GC in line-1?
can anyone explain how come 2 objects are eligible for GC here?

[Jesper de Jong]

This question has been discussed before:

One object eligible for garbage collection?
Garbage Collection

[Anuradha Prasanna]

Thanks, i got it!