DHCP snooping on Cisco Nexus 1000V Series Switches acts like a firewall between untrusted hosts and trusted DHCP servers by doing which of these？ （）

A. validates DHCP messages received from untrusted sources and filters out invalid response messages from DHCP servers
B. intercepts all ARP requests and responses on untrusted ports
C. builds and maintains the DHCP snooping binding database， which contains information about untrusted hosts with leased IP addresses
D. uses the DHCP snooping binding database to validate subsequent requests from untrusted hosts
E. limits IP traffic on an interface to only those sources that have an IP-MAC address binding table entry or static IP source entry