Which two actions should you recommend?

Contoso, Ltd., and Fabrikam, Inc., are partner companies.
Each company has an Exchange Server 2013 organization in a data center that is connected to the
Internet. All of the Exchange servers in both of the organizations have the Client Access server role
and the Mailbox role installed.
The data centers connect to each other by using a redundant high-speed WAN link.
The following mail exchanger (MX) records are configured:
Contoso.com MX 10 mail.contoso.com
Fabrikam.com MX 10 mail.fabrikam.com
You need to recommend a solution for inbound mail flow.
The solution must meet the following requirements:
Users in both companies must receive email from the Internet if either of the Internet links fails.
Mail from the Internet to contoso.com must be received by mail.contoso.com if the Internet link at
the Contoso data center is available.
Mail from the Internet to fabrikam.com must be received by mail.fabrikam.com if the Internet link at
the Fabrikam data center is available.
Which two actions should you recommend? (Each correct answer presents part of the solution.
Choose two.)

A.
Create the following DNS records:
* Contoso.com MX 20 mail.fabrikam.com
* Fabrikam.com MX 20 mail.contoso.com

B.
Create the following DNS records:
* Contoso.com MX 10 mail.fabrikam.com
* Fabrikam.com MX 10 mail.contoso.com

C.
For each organization, configure an internal relay domain and a Send connector.

D.
For each organization, configure an external relay domain and a Receive connector.

E.
Create the following DNS records:
* Contoso.com MX 5 mail.fabrikam.com
* Fabrikam.com MX 5 mail.contoso.com

Explanation:
A) Use a priority above 10.
D) “Each company has an Exchange Server 2013 organization”. We therefore need to configure an
External relay. An Internal relay would be used if the two SMTP domains were in the same Exchange
organization. We also need to configure a Receive connector in each organization to allow the
organization to receive email destined for the other organization.