What should you create?

You need to configure identity synchronization.

What should you create?
A . a second Azure Active Directory Connect sync server
B . backups of all on-premises server farms
C . backups of all Azure VMs
D . a second Azure Active Directory Connect staging server
E . a second Azure Active Directory directory

Answer: D

Explanation:

/ High availability is required for account synchronization services.

/ Any configuration changes to account synchronization must be tested without disrupting the services.

Explanation:

https://docs.microsoft.com/en-us/azure/active-directory/connect/active-directory-aadconnect-topologies#staging-server