The system administrator notices that after running netstat -rn， several small c’s are showing up under the flags columns， and routes that were not defined are also showing up. How can these cloned routes be stopped？（）

• A、 By default cloned routes are turned on.  To turn cloned routes off issue the command：      #no -o tcp_pmtu_discover=0       #no -o udp_pmtu_discover=0       and add to the rc.net or rc.bsdnet file for next reboot
• B、 By default cloned routes are turned on.  To turn cloned routes off issue the command：        # no -o tcp_pmtu_discover=1        #no -o udp_pmtu_discover=1         and add to the rc.net or rc.bsdnet file for next reboot
• C、 By default cloned routes are turned on.  To turn cloned routes off issue the command：         #no -o ipforwarding=0         and add to the rc.net or rc.bsdnet file for next reboot
• D、 By default cloned routes are turned on.  To turn cloned routes off issue the command：         #no -o ipforwarding=1         and add to the rc.net or rc.bsdnet file for next reboot