you need to prevent the databases from mounting in Site1

Your network contains a single Active Directory forest. The forest contains two sites named Site1 and Site2.
You have an Exchange Server 2016 organization. The organization contains two servers in each site. You have
a database availability group (DAG) that spans both sites. The file share witness is in Site1.
If a power failure occurs at Site1, you plan to mount the databases in Site2.
When the power is restored in Site1, you need to prevent the databases from mounting in Site1.
What should you do?

A.
Disable AutoReseed for the DAG.

B.
Implement an alternate file share witness.

C.
Configure Datacenter Activation Coordination (DAC) mode.

D.
Force a rediscovery of the network when the power is restored.

Explanation:
https://technet.microsoft.com/en-us/library/dd979790(v=exchg.150).aspx