What command should you use to remove the deferred user job that has the job number 5?

To remove a deferred job in the at job scheduling system, the command to use is atrm followed by the job number. In this case, the correct command is atrm 5, which specifically targets job number 5 for removal from the queue of scheduled tasks.

This command is specifically designed for the at service, which allows users to schedule one-time jobs to be executed at a specified time. Using atrm followed by the job number effectively eliminates the specified job from the user's at queue.

The other options are not suitable for this task. For instance, atq simply lists the currently scheduled jobs, and while it is useful to check the status and list of jobs, it does not remove any jobs. The crontab -r command is used to remove all scheduled cron jobs for the current user, which is a different scheduling system entirely and does not pertain to one-time jobs specified by the at command. Finally, the systemctl stop command is utilized to stop a service managed by systemd, which is unrelated to job scheduling and would not affect jobs scheduled using the at command.

Thus, using atrm 5 is the correct choice for removing the specific deferred