What is a Common Gateway Interface (CGI) application?

A Common Gateway Interface (CGI) application is fundamentally a way for web servers to interface with executable programs, enabling the server to process user inputs and generate dynamic content. Specifically, option A accurately describes this functionality, as CGI applications take data submitted by users—often from forms on a webpage—and relay that information to a web server or a database server for processing. This means that when a user fills out a form and submits it, the CGI acts as an intermediary that captures that data and allows the server to respond accordingly.

In a typical CGI scenario, the user input is processed in real time, enabling actions such as querying a database, generating a webpage based on user preferences, or executing scripts that result in dynamic content being delivered back to the user's browser. Such capabilities are crucial for creating interactive web applications.

The other options describe different technologies or functionalities that do not align with the principles of CGI. For instance, while database management systems and APIs can play roles in web development, they do not serve the same purpose as a CGI application in facilitating communication between a web browser and a web server based on user input. Therefore, option A is the most accurate representation of what a CGI application is and does.