Final answer:
Option D, o, is not a browser prefix. Browser prefixes are used to add new features to web browsers before they are standardized.
Step-by-step explanation:
The answer is option D. o is not a browser prefix. Browser prefixes are used to add new features to web browsers before they are standardized. They are used to ensure that the new features work correctly across different browsers. Examples of browser prefixes include edge, moz, and webkit.