Inheritance allows the following in C++ program:

Question

Accepted Answer

The correct option is (4):
Inheritance is a fundamental pillar of Object-Oriented Programming (OOP) in C++ that allows a new class (derived class) to acquire properties and behaviors from an existing class (base class). This mechanism directly enables all the listed options. **Class Re-usability** is achieved because the derived class automatically incorporates the base class's implemented code, eliminating the need for code duplication. By structuring classes in parent-child relationships, inheritance is the core tool for **Creating a hierarchy of classes**, which models real-world "is-a" relationships (e.g., a Dog is an Animal). Furthermore, **Extendibility** is facilitated because the derived class can add new features or specialize existing ones through method overriding without ever modifying the proven, existing base class code, thereby making the system flexible and easy to maintain. Since all three options are intrinsic benefits and functions of inheritance, "All options are correct" is the comprehensive and correct choice.

The incorrect option is (1):
Class Re-usability is a major benefit of inheritance, as it prevents redundant code by allowing derived classes to use base class members. However, selecting this option alone is incomplete. Inheritance is a structural relationship, and choosing only the benefit of code reuse overlooks the fundamental design role of creating a class hierarchy and the developmental advantage of extendibility. The question asks what inheritance *allows*, and it allows for more than just re-using code; it fundamentally allows for structural organization and safe modification.

The incorrect option is (2):
Creating a hierarchy of classes is indeed the structural foundation upon which inheritance operates, as it organizes code into a logical parent-child tree. This modeling ability is vital for good OOP design. Nonetheless, this option only describes the *means* or structure of inheritance, not the full range of its *benefits*. The question requires the selection of all valid outcomes, and since inheritance also yields the functional advantages of code re-usability and extendibility, this option is too narrow to be the complete answer.

The incorrect option is (3):
Extendibility, the ability to add new functionality without impacting existing base code, is one of the most powerful reasons to use inheritance. It allows the system to grow safely over time. Despite its importance, just like the other single options, it is only a partial answer. Inheritance is not exclusively used for extension; it is also used for the primary goals of re-using existing, proven code and establishing the core structural hierarchy of the program. Therefore, choosing only "Extendibility" is insufficient to describe all the allowances of inheritance.