To ensure that all servers for the accounting department are backed up and any new servers added to the department are automatically included in the protection group, the best approach is to use an Active Directory (AD) based protection group. Therefore, the correct answer is A: Create an Active Directory based protection group targeted at an Active Directory security group.
By leveraging an AD-based protection group, the Veeam administrator can specify an AD security group that encompasses all user accounts or computer accounts (in this case, servers) associated with the accounting department. As new servers are introduced and added to this AD security group, Veeam Backup & Replication will automatically detect these new members during its periodic rescan (which can be scheduled as per the administrator's preferences) and include them in the protection group. This method not only automates the inclusion of new servers into the backup routine but also simplifies the management of backup policies for dynamically changing environments such as the accounting department's server infrastructure.

Explanation
According to the Veeam Backup & Replication user guide1, you can use the File Level Restore wizard to restore files and folders from VM guest OSes that run Windows2. The wizard allows you to choose how to access the VM guest OS: through network or through VIX2VIX is a VMware API that enables programmatic access to virtual machine operations3.
Therefore, if you want to restore a file on a Windows VM hosted on vSphere and the mount server cannot connect to the VM through the network, you can use VIX as an alternative method of access2. This will allow you to restore the file directly to its original location without downloading it locally or starting an Instant VM Recovery session.

https://helpcenter.veeam.com/docs/backup/vsphere/backup_copy_modes.html?ver=120#changin g-backup-copy-modes

In Veeam ONE, the remaining capacity of each backup repository server can be viewed under the Data Protection View. This section provides detailed information about the storage utilization and remaining capacity of backup repositories, allowing administrators to effectively monitor and manage storage resources.