What does polymorphism in programming allow?

Polymorphism in programming enables different data types, particularly objects of different classes, to be treated as objects of a common superclass. This is particularly beneficial in object-oriented programming, where polymorphism allows for methods to process objects differently based on their actual derived class types while maintaining a unified interface.

For instance, consider a method that accepts a parameter of a common superclass type. You can pass any subclass instance to that method, allowing it to execute the appropriate behavior depending on the actual class of object being processed. This capability enhances code flexibility and reusability, as the same method can operate on various data types that share a common interface.

The other options reflect concepts that may relate to programming but do not accurately define what polymorphism entails. While the coexistence of multiple instances of a class is relevant to object-oriented programming, it does not capture the essence of polymorphism. Similarly, the retrieval of data structures and limitations on class functionality are not central to the, nor accurately expand upon, the concept of polymorphism.