Answer:
D) Most GUI editors allow you to easily preview and test your pages in the browser(s) of your choice.
Explanation:
A) You would need an additional tool for test with built-in code validators or validation sites.
B) WYSIWYG allows content to be edited in a form that resembles its appearance, not exactly as they will appear and work on the Web
C) It is not convenient to publish pages to the Web,then make change and republish them.