What term refers to the interface used to program graphical user interface components, typically used by developers rather than end users?

• A. OS
• B. API
• C. GUI
• D. CLI

Answer: (B)

This item tests understanding of the programming interface used to build GUI elements. The term is the API, an application programming interface. An API is a defined set of tools, functions, classes, and conventions that a GUI toolkit or library exposes so developers can create and manage windows, buttons, layouts, and event handling without worrying about the underlying details of the system. It’s the developer-facing interface used to construct software, including graphical interfaces.

In contrast, the graphical user interface is what end users actually see and interact with. The command-line interface is a text-based way to interact with programs, not a toolkit for building GUI components. And the operating system provides the overall environment and core services, but not the specific programming interface for GUI widgets.