You deploy two Windows Server 2008 R2 Hyper-V servers. You manage the servers by using Microsoft System Center Virtual Machine Manager （VMM） 2008 R2. You need to ensure that you can restore virtual machines （VMs） in the event of a hardware failure.   What should you do？（）

• A、Use a PowerShell script to create a snapshot of each VM. Run the script every 60 minutes on each Hyper-V server
• B、Use a PowerShell script to create a checkpoint of each VM. Run the script every 60 minutes on each Hyper-V server
• C、Use a PowerShell script to pause， export， and start each VM， and then to copy the export to the opposite Hyper-V server. Run the script once per day on each Hyper-V server
• D、Use a PowerShell script to shut down， export， and start each VM， and then to copy the export to the opposite Hyper-V server. Run the script once per day on each Hyper-V server