Your network contains an Active Directory domain named contoso.com. The domain contains a  member server named HVServer1. HVServer1 runs Windows Server 2012 and has the Hyper-V server role installed. HVServer1 hosts 10 virtual machines. All of the virtual machines connect to a virtual switch named Switch1. Switch1 is configured as a private network. All of the virtual machines have the DHCP guard and the router guard settings enabled.You install the DHCP server role on a virtual machine named Server 1. You authorize Server1 as a DHCP server in contoso.com. You create an IP scope.You discover that the virtual machines connected to Switch1 do not receive IP settings from Server1. You need to ensure that the virtual machines can use Server1 as a DHCP server.  What should you do？（）

• A、Enable MAC address spoofing on Server1
• B、Disable the DHCP guard on all of the virtual machines that are DHCP clients
• C、Disable the DHCP guard on Server1
• D、Enable single-root I/O virtualization （SR-IOV） on Server1