A. BitLocker is a volume-level encryption technology. When the password for a BitLocker protected USB device is entered, the volume becomes unprotected for the OS instance. If the user who unlocked the device doesn't disconnect the device before logging off, or if another user logs onto the same machine using Switch User, the other users will still have access to the USB device's content.
In addition, any user who is an administrator has remote access to the USB device, so those users would also be able to access the data once the USB device is unlocked by the local user.
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