1. Dozens  da = new Dozens;
Here one array object is made i.e da. It contains 3 objects which are null(default vale for objects) currently as they have not been assigned any value.
2. da = new Dozen();
Dozens d = new Dozens();
2 objects created here One assigned to d and another one d.
So, I think 3 objects are created. But answer says 5 objects
d = null and d = null. Both refer to same object so only 1 Object is eligible for GC but answer says 2 objects