What does 'polymorphism' refer to in object-oriented programming?

Polymorphism in object-oriented programming refers to the ability to treat objects of different classes in a uniform way. This concept allows for a single interface to represent different underlying forms (data types). The primary benefit of polymorphism is that it enables methods to be defined that can work on objects of various classes, leading to more flexible and reusable code.

For instance, consider a function that takes an object as a parameter. With polymorphism, this function can accept objects from different classes as long as they share a common base class or interface, allowing the same function to operate differently depending on the specific object type passed to it. This capability enhances code organization and efficiency, facilitating the implementation of concepts like interfaces and abstract classes.

In contrast, options that focus on inheritance, code versions, or compiling across languages do not capture the essence of polymorphism. Inheritance refers specifically to a class acquiring properties and behaviors from another class, while maintaining multiple versions of a program and compiling code in various languages do not pertain to the treatment of objects in a consistent manner.