An administrator performs an audit on the /usr filesystem and finds the following permissions： -rwsr-xr-x 1 root sys 514288 Jun 18 09：40 /usr/local/bin/nmon Which of the following methods can the administrator use to remove a potential security risk（）

A. rm /usr/local/bin/nmon
B. chmod u-s /usr/local/bin/nmon
C. Reinstall the file from the appropriate fileset
D. chmod go-rx /usr/local/bin/nmo