Machine policy templates can be assigned based on certain attributes of a machine. A customer organizes their machines based on the following requirements： The machines are all placed in specific Organizational Units in the Active Directory. The customer has Citrix Servers， and they have a specific naming convention meant only for their Citrix Servers. The customer has DHCP enabled for all the client machines. The customer has made it clear that they should not need to change anything in the existing infrastructure. Given these requirements， which single assignment attribute would be chosen for assigning machine policy templates？（）