What does each extension call?

• A. A configuration file that defines how the extension loads.
• B. A user authentication module.
• C. A specific routine or function.
• D. A data export format.

Answer: (C)

When an extension is used, what gets invoked is a specific routine or function that the extension exposes for the host to call. A call represents invoking a named operation with input values, and it returns a result or signals completion. This is how extensions perform tasks: the host asks the extension to do something by calling its function, and the function runs to produce output or carry out an action. The other ideas describe setup or components rather than a single action: a configuration file tells the host how to load the extension, not an operation to perform at runtime; a user authentication module is a part of the system that handles login, not a single callable task; a data export format is about how data is structured for export, not a function you execute.