Which feature allows a user to group open applications into one view on macOS?

Mission Control is the feature that allows users to see all open applications grouped together in a single view on macOS. This feature provides an organized overview of all running applications and their windows, enabling users to quickly switch between them or access different desktops. Mission Control enhances productivity by allowing users to manage their open applications more effectively, facilitating multitasking and organization on the desktop.

The other options refer to different functionalities. Expo Mode does not exist as a recognized feature in macOS; it may be a confusion with other operating systems or a misinterpretation. Multi-window Mode is not a specific feature of macOS recognized within its user interface; macOS typically manages open applications through other means, such as Mission Control. Lastly, the Application Switcher is a feature that allows users to switch between applications using keyboard shortcuts (like Command + Tab), but it does not provide a grouped view of open applications in the same way that Mission Control does.