You have a Windows Server 2008 R2 Hyper-V server. One of the virtual machines （VMs） that is hosted on the server has a directly attached physical disk. You need to back up the VM. What should you do？（）

• A、Perform a full server backup on the VM.
• B、Perform a critical-volume backup on the VM.
• C、Perform a full server backup on the host server.
• D、Perform a critical-volume backup on the host server.