Which principle of Object-Oriented Programming involves bundling data with methods that operate on that data?

The principle of Object-Oriented Programming that involves bundling data with the methods that operate on that data is encapsulation. Encapsulation is a fundamental concept where an object's internal state (its data) is kept private and protected from outside interference and misuse. By encapsulating both data and the methods that manipulate that data within a single unit, it promotes a clear separation between an object's internal representation and its external interface.

This practice helps maintain the integrity of the data by restricting access through public methods (getters and setters) that control how the data can be read or modified. As a result, encapsulation leads to more manageable and understandable code, reduces complexity, and facilitates maintenance and code reuse.

The other principles, while integral to Object-Oriented Programming, do not directly relate to bundling data with methods in the same way that encapsulation does. Inheritance relates to deriving new classes from existing ones, polymorphism allows for methods to be defined in multiple forms, and abstraction focuses on hiding complex implementation details while exposing only the essential features.