Your company has an Active Directory Domain Services (AD DS) domain. All servers run Windows Server 2008 R2. You activate the Key Management Service (KMS) on a server to handle volume activation for your Windows 7 client computers. Windows 7 client computers are not being activated. The KMS licensing status is shown as Licensed. The Windows Event Log does not contain any corresponding activation-related events. You need to ensure that the KMS server can activate Windows 7 client computers. What should you do?（）

A. Run the slmgr.vbs /dlv command.
B. Run the slmgr.vbs /ato command.
C. Add a DNS A record pointing to the KMS server.
D. Add a DNS SRV record pointing to the KMS server.