What is a virtual method in object-oriented programming?

A virtual method in object-oriented programming is a function defined in a base class that is intended to be overridden in one or more derived classes. This concept is fundamental to the idea of polymorphism, which allows for dynamic method resolution at runtime. When a method is declared as virtual, it enables the derived class to provide its specific implementation of that method, thereby allowing objects of the derived class to be treated as objects of the base class while still invoking the overridden method.

The primary goal of virtual methods is to allow different behaviors in derived classes without changing the interface that uses these objects. This helps in achieving more flexible and maintainable code, where different classes can be used interchangeably as long as they adhere to the same interface.

The other options describe different concepts. For instance, a method that cannot be inherited is not a virtual method but may refer to a final or sealed method in some languages. A private method is not accessible to derived classes, which means it cannot be overridden. Lastly, a method that is automatically executed could refer to constructors or destructors but does not accurately define the purpose or nature of virtual methods. Therefore, the essence of virtual methods lies in their ability to be overridden, making the first option the most accurate representation.