HOTSPOT
Your network contains two Active Directory sites named Site1 and Site2. Both sites contain an equal
number of users. Each site contains two Exchange Server 2013 Mailbox servers.
You need to recommend a high-availability solution that meets the following requirements:
If a single Mailbox server fails, the active mailbox database copies on that server
must fail over to a Mailbox server in the same site.
If both Mailbox servers in the same site fail, the active mailbox databases copies must be
switched over to the other site manually.
If a WAN link fails, multiple copies of the same mailbox database must not be activated in both
sites simultaneously.
How should you configure the database availability groups (DAGs)? (To answer, configure the
appropriate options in the answer area.)
Answer: 
This seems correct. You won’t be able to fail over to the other site if you don’t have any copies of the databases, so you would have 1 DAG with all of the servers from all sites as members with copies of the DB’s.
Enabling DAC mode will allow you to fail it over manually.