Which of the following enables third-party developers to create capabilities to extend an application?

A plug-in, also known as an add-on or extension, is a software component that adds specific features to an existing computer program. This modular design allows third-party developers to create new functionalities that integrate seamlessly with the main application, expanding its use cases without altering its core code.

A virtual machine is an emulation of a computer system, used to run operating systems or applications in an isolated environment, not primarily to extend the capabilities of a host application.

A hotfix is a software patch applied to resolve a specific bug or security vulnerability, rather than to add new, extended capabilities to an application.

JavaScript is a programming language primarily used for web development to create interactive content, but it is not the general term for a component that extends an application's capabilities, although some applications might use scripting for extensibility.