Which of the following statements describe the Polymorphism principle of the GRASP approach to object-oriented design?

Options:

1. Superclass variables are typically exposed
2. A child class can be substituted for a parent class
3. An object can be used as if it were an object of its superclass while still using its overridden methods
4. A child class and a parent class have different types
5. Subclass-specific versions of a superclass method are implemented in the subclasses
6. Methods of the superclass can be used in the subclasses
7. Polymorphism is accomplished through inheritance and overriding