Question

I'm confused as to if subclasses can call the supers without any implementation and what the right answer is

Answer 1

E

Step-by-step explanation:

Since Example1 and Example2 inherit from Example0, all classes have the method doNothing() at their disposal, so you can call it from e0, e1 and e2.

However, the arguments of this method are Example1 and Example2, so you cannot pass Example0 as a first argument, and you cannot pass Example0 or 1 as a second argument. That only leaves answer E.

You can call the inheritance relation an "is a kind of" relation. So Example1 is a kind of Example0, and Example2 is a kind of Example1, but also Example2 is a kind of Example0.

Now you can understand why e2 can be passed as an argument for Example1, because e2 is a kind of Example1.