问题：

[单选]

Your network consists of a single Active Directory domain.
You install a new backup program. The backup program requires a service account.
You create a service account in the domain.
You need to ensure that the service account can back up all member servers and client computers in the domain.
You must ensure that the service account cannot be used to restore files and folders.
What should you do?（）

A . Add the service account to the domain Backup Operators group.
B . Add the service account to the Backup Operators group on every server and every client computer.
C . Assign the Back up files and directories user right by using a Group Policy object (GPO).
D . Assign the Impersonate a client after authentication user right by using a Group Policy object (GPO).