Final answer:
Run-time (late-binding) polymorphism involves the runtime environment, not the compiler, deciding which overridden method to invoke based on the actual object's type. This enables different class objects to respond differently to the same method call, a feature of object-oriented programming.
Step-by-step explanation:
In run-time (late-binding) polymorphism, it is not the compiler but rather the runtime environment (like the Java Virtual Machine or the .NET Runtime, for instance) that decides which overridden method to invoke. This form of polymorphism is characterized by an object's ability to take on many forms. In dynamically typed languages or in languages that support dynamic method invocation, the exact method that is called is determined at runtime based on the actual object's type, not the type with which the variable was declared. This allows for objects of different classes that are related by inheritance to respond differently to the same method call.
To be more precise, when you call a method on an object that is capable of run-time polymorphism, the invoked method will be the one provided by the actual class of the object (which might be a subclass of the type of the reference used to invoke the method). This ability to change the method implementation dynamically is what makes polymorphism a powerful feature in object-oriented programming (OOP). The actual process involves something called a virtual method table or similar mechanism in many OOP languages. For example, in Java, the JVM determines the appropriate method to call at runtime, based on the actual object's class.