To view all items in the Sitecore content tree, which option is crucial to have selected?

To view all items in the Sitecore content tree, it is essential to have the 'Show hidden items' checkbox selected. By default, Sitecore may not display items marked as hidden, which are typically used for various purposes like workflows, unpublicated items, or administrative references. Selecting this option ensures that you can see all items, including those that are otherwise not visible in the standard view, allowing you to manage and navigate through the entire content tree effectively.

The other choices focus on specific aspects of item visibility. For instance, the option to show only published items would restrict the view to items that have been published, excluding any unpublished or draft items. The 'Expand all items' option would simply open up all expanded nodes for easier navigation but does not impact visibility. Lastly, the 'Use filters' option allows for targeted searching through items based on specific criteria, which also would limit visibility depending on the filters set. Hence, the selection of the 'Show hidden items' checkbox is crucial for a complete view of the content tree.