What should you back up?

Your network contains an Active Directory domain named contoso.com. All servers run
Windows Server 2012 R2. The network contains a System Center 2012 R2 Data Protection
Manager (DPM) deployment.
The domain contains six servers. The servers are configured as shown in the following table.

You install System Center 2012 R2 Virtual Machine Manager (VMM) on the nodes in
Cluster2.
You configure VMM to use a database in Cluster1. Server5 is the first node in the cluster.
You need to back up the VMM encryption key.
What should you back up?

A.
A full system backup of Server1

B.
A full system backup of Server3

C.
A backup of the Windows\DigitalLocker folder on Server5

D.
A backup of the Windows\DigitalLocker folder on Server1