What is the best recommendation to achieve the goal?

Your company has two offices. The offices are located in San Francisco and Los Angeles.
Each office contains a data center.
Each data center has a local connection to the Internet.
You deploy an Exchange Server 2016 organization named Contoso and install three servers in each data
center.
All of the servers are members of a single database availability group (DAG). Each data center hosts 2,000
mailboxes that replicate to the other data center.
You create four records in DNS. The records are configured as shown in the following table.

You need to recommend a client access solution for the organization to meet the following requirements:
When connecting from the Internet, all users must connect to the same namespace for Outlook on the Web.
If a connection to the Internet fails at one data center, all users must be able to access their mailbox from theInternet.
When connecting from the Internet, all user connections to Exchange ActiveSync must be balanced equally
across both data centers.
What is the best recommendation to achieve the goal? More than one answer choice may achieve the goal.
Select the BEST answer.

A.
in the San Francisco office, configure the internal URLs of the servers to use the internal
URLofsfmail.contoso.com. In the Los Angeles office, configure

B.
in the San Francisco office, configure the external URLs of the servers to use the internal
URLofsfmail.contoso.com. In the Los Angeles office, configure

C.
Deploy a hardware-based load balancer to each office and configure all of the internal URLs to use
mail.contoso.com.

D.
Deploy a hardware-based load balancer to each office and configure all of the external URLs to use
mail.contoso.com.