Which option best defines encapsulation in object-oriented programming?

Encapsulation is a fundamental concept in object-oriented programming that refers to the bundling of data and the methods that operate on that data into a single unit, typically called a class. This approach promotes modularity and helps hide the internal state of an object from the outside world, exposing only what is needed through public methods. By encapsulating data, it is possible to protect the integrity of that data and prevent unintended interference or misuse.

This process not only organizes code effectively but also enforces restrictions on how the data is accessed or modified, typically through getter and setter methods. Thus, encapsulation serves to create a clear boundary around an object's data, allowing for a controlled interaction with that data while maintaining the object's integrity. This makes option A the best choice to define encapsulation within the context of object-oriented programming.

The other options pertain to different aspects of object-oriented programming. Inheritance, which is mentioned in the second option, refers to the mechanism whereby a new class can inherit properties and behaviors from an existing class. Abstract classes relate to defining general blueprints for other classes without implementing all the details of their methods, while representing real-world entities with objects is an overarching principle of object-oriented design, not a specific definition of encapsulation.