A browser ___ is a separate program that adds a variety of useful features to the web browser, such as sending instant messages or playing mobile-style games.

The correct option is;

Extension

Explanation:

A browser extensions are available small applications plug-ins that allow the modification of the web browser by customizing and changing how information flows through the browser. Browser capabilities include the hosting of varying forms of browser extensions, and settings for ad blocking. Web experiences are vastly enhanced by browser extensions by providing personalized experience.

answer; code of ethicsi believe is the correct answer;