An ad extension, if present, will always serve.

The statement is False because an ad extension, if present, does not always serve. Ad extensions, such as site link extensions, call extensions, or location extensions, are additional elements added to ads to provide extra information and improve visibility. However, their appearance is not guaranteed with every ad impression. Ad extensions are shown based on factors like ad rank, available space, and the relevance of the extension to the search query or user’s context. For example, if the ad rank is not high enough, or if there is not enough room on the search results page, the extension might not appear. Therefore, even if an ad extension is set up, its display depends on the conditions at the time of the auction and other factors, which means it doesn't always serve with every ad.