When limiting access to removable hard drives, which command-line tool should the technician use to apply the new policy?

The command-line tool that should be used for applying Group Policy changes, such as limiting access to removable hard drives, is the Group Policy Update command (gpupdate). This command is essential when you want to refresh Group Policy settings on a computer without needing to wait for the next scheduled update.

Using gpupdate forces the system to re-evaluate and apply any changes that have been made to Group Policy Objects (GPOs), which is necessary after configuring policies that may restrict access to hardware like removable drives. This ensures that the new policy takes effect immediately.

The other options are used for different purposes. For instance, diskpart is primarily for managing disks and partitions, which does not apply directly to the application of Group Policy settings. gpresult provides information about the applied Group Policies and their results but does not apply changes. The net use command is for managing network connections and shared resources, not for applying Group Policy settings.

Thus, using gpupdate is the best choice for the task of applying new policies regarding removable hard drives.