Which of the following is not a browser prefix?

The choice identified as not being a browser prefix is accurate because each of the other options are indeed recognized as browser prefixes used in CSS to provide support for various web features in different browsers.

The prefix "moz" is associated with Firefox, allowing developers to apply CSS rules specifically for that browser. Similarly, "webkit" is used for WebKit-based browsers like Safari and older versions of Chrome, enabling experimental features that may not yet be standardized. The prefix "o" pertains to Opera and is used in the same way to tailor styles specifically for that browser.

On the other hand, "edge" does not function as a prefix in this context. While Microsoft Edge does use a variant of the "webkit" engine for improved compatibility, it doesn't have a widely recognized CSS prefix like the others do. Therefore, it stands out as the correct answer to the question about which is not a browser prefix.