What should you do to activate thumbnails in the Image mode?

To activate thumbnails in Image mode, clicking the Show/Hide Button is the correct action. This button is specifically designed to control the visibility of thumbnails, allowing you to toggle their display in the interface. When you click this button, the thumbnails of images will appear, making it easier to view and manage your images visually.

The other options provided do not directly relate to activating thumbnails. Marking up images can affect how they are processed or categorized, but it does not influence the appearance of thumbnails. Utilizing the search tool may help you locate images, but it does not activate thumbnail view. Similarly, opening the redaction menu is related to redaction tasks rather than the visibility of image thumbnails. Thus, employing the Show/Hide Button ensures you can efficiently access and manage the images you are working with.