Joe, a user, asks a systems administrator to schedule the daily execution of a custom script. Which of the following commands will allow the systems administrator to set up Joe's cron job?

The `crontab -r -u joe` command removes all cron jobs for the user "joe" without prompting, which is destructive and not for setting up new jobs.

The `crontab -e -u joe` command opens the crontab file for the user "joe" in a text editor, allowing the administrator to add, modify, or delete scheduled tasks (cron jobs) for that user. The `-e` flag stands for "edit", and `-u` specifies the user.

The `crontab` command does not have a `-n` option; this is not a valid flag for managing cron jobs.

The `crontab -l -u joe` command lists the existing cron jobs for the user "joe", but it does not allow for adding or editing new jobs.