Polymorphism vs Inheritance

Question

Suppose I have two classes: Animal and Dog. Dog is a subclass of Animal. I do the following code:

Animal a = new Dog();

Now I can call methods

Answer 1

Polymorphism allows you to write a method that works for any Animal:

public void pet(Animal animal) {
   ...
}

This method would accept Dog, Cat, etc, including subclasses of Animal that are yet to be written.

If the method were to take Dog, it would not work for Cat etc.