The Company security administrator wants to prevent DHCP spoofing.  Which statement is true  about DHCP spoofing operation？（）

• A、 DHCP spoofing and SPAN cannot be used on the same port of a switch.
• B、 To prevent a DHCP spoofing， the DHCP server must create a static ARP entry that cannot be  updated by a dynamic ARP packet.
• C、 To prevent a DHCP spoofing， the switch must have DHCP server services disabled and a static  entry pointing towards the DHCP server.
• D、 DHCP spoofing can be prevented by placing all unused ports in an unused VLAN.
• E、 None of the other alternatives apply.