You’ve just customized a report and want it to appear in the left-hand navigation. To do this, which section should you add the report to?

To make a customized report visible in the left-hand navigation of Google Analytics, you must add it to a "Collection." Collections are curated sets of reports that appear in the navigation panel, allowing users to quickly access relevant information. "Explore" is a section for advanced analysis and custom reporting, but it doesn't directly influence the left navigation. "Library" is where you manage and create reports, but adding a report to the Library doesn't automatically display it in the navigation; it needs to be part of a Collection. "Admin" is for managing property and account settings, not for organizing report navigation.