What can be used to display a navigation menu without showing the main navigation tree?

The correct choice is a menu, which can be utilized effectively to display navigation options without having to present the entire main navigation tree. Menus are versatile UI elements that allow users to access various sections or functionalities of an application in a more concise format. This means that instead of overwhelming users with a comprehensive navigation tree that encompasses all options, a menu can present curated choices that are relevant to the user experience, offering a cleaner and more focused interface.

This usage is particularly beneficial in scenarios where screen space is limited or when it's essential to streamline the user experience. Menus can often be designed to adapt dynamically to the context or user role, making them a practical choice for navigation purposes without the visual bulk of a complete navigation tree.

The other options have their own characteristics but do not specifically align with the requirement of displaying navigation without the main navigation tree in the same way. For example, a sidebar menu typically integrates with the main navigation structure and is visible on the side of the application, while dropdown menus, although versatile, are usually employed for sub-options under a larger menu item. A content menu often implies a contextual menu that appears based on user actions and might not serve the same navigation purpose as a traditional menu used for linear navigation.