What type of software adds functionality to a browser?

The correct answer is that extensions add functionality to a browser. Extensions are small software applications that integrate directly with web browsers to enhance their capabilities. They can provide a variety of features, such as ad-blocking, password management, grammar checking, and many other tasks that improve the user's experience while browsing the internet.

While plug-ins also add functionality to browsers, they are often specific to certain types of content, like video or audio playback, and may require additional installations outside the browser. Extensions, on the other hand, are easier to install and manage directly through the browser's interface, allowing users to tailor their browsing experience more effectively.

Applications refer to standalone programs that may not necessarily integrate with a browser. Frameworks, on the other hand, are collections of tools and libraries used primarily by developers to build software applications, rather than enhancing browser functionality.