A web application is client/server software that uses a web server as its server and what type of software as its client?

The correct choice is web browser because web applications are designed to be accessed and interacted with through a web browser. A web browser serves as the client in this client/server model, allowing users to request web pages, send data to the web server, and receive responses in the form of HTML, CSS, JavaScript, and other web content. Through the browser, users can utilize the full functionality of web applications, enabling interaction with the server-side components that process and manage data.

The other options do not serve as clients for web applications. A file explorer is primarily used for managing files and directories on a local system, not for interacting with web applications. A database management system is concerned with managing databases and is typically used on the server side rather than as a client for web-based interactions. A text editor is designed for editing text files and does not provide the functionality required to access or interact with web servers.