Object-oriented programming: Is multilevel inheritance allowed (A → B → C → D)? Select the statement that best reflects C++/Java-style inheritance rules.

Introduction / Context: Multilevel inheritance means a class derives from a class that itself derives from another class, forming a chain such as A → B → C → D. This is a foundational capability in classical OOP languages like C++ and is conceptually supported in Java via single inheritance of classes (interfaces are separate). The question tests whether such layered hierarchies are permitted.

Given Data / Assumptions:

• We consider typical OOP languages with single inheritance of implementation for classes (e.g., C++, Java).
• The chain A → B → C → D represents class D extending C, which extends B, which extends A.
• No multiple-inheritance-of-classes is being asserted—only multilevel (transitive) inheritance.

Concept / Approach: In multilevel inheritance, every class in the chain inherits the accessible members of its parent. Constructors and destructors (or finalizers) are invoked in well-defined orders. Method overriding, virtual dispatch (C++) or dynamic dispatch (Java), and polymorphism apply transitively.

Step-by-Step Solution:

Verification / Alternative check: Many standard libraries organize types in inheritance chains (e.g., Java’s java.io hierarchy). Unit tests that instantiate D can call methods from A, B, and C according to access rules.

Why Other Options Are Wrong:

• Incorrect: Denies a supported language feature.
• Only with interfaces / Only with abstract classes: Not required; concrete classes may participate.
• Runtime dependent: This is a compile-time language feature, not runtime dependent.

Common Pitfalls: Confusing multilevel inheritance (legal) with multiple inheritance of classes (restricted in Java). Poorly designed deep chains can harm maintainability, but that is a design smell, not a prohibition.

Final Answer: Correct