It has been determined that print jobs from an application are not being removed from the system after they have been printed. To remove these jobs from the /var/spool directory, which cron entry will remove files more than 7 days old?（）

• A、 find /var/spool/lpd/qdir -mtime -7 -type f -exec rm -f {}/
• B、 find -name /var/spool/* -f rm {}/
• C、 find -name /var/spool/lpd/* -exec rm {}/
• D、 find /var/spool/lpd/qdir -mtime +7 -type f -exec rm -f {}/