explain the real-word example of multilevel inheritance?
Suppose we have classes Animal and Mammal. Mammal is derived from Animal because in fact, mammal is animal. Now suppose we add new class Elephant. Class Elephant is derived from Mammal because elephant is a mammal mammal is animal. All these 3 classes form multilevel inheritance: Animal->Mammal->Elephant because Elephant is derived from Mammal that is derived from Animal.