You are evaluating the planned deployment of the additional Exchange Server 2013 servers.
You need to recommend changes to the DNS records to ensure that email messages are routed to the Detroit site if the servers in the New York site are unavailable.
What should you recommend adding?
A. An MX record that has a preference value of 10 that points to EX4
B. An MX record that has a preference value of 20 that points to EX4
C. An MX record that has a preference value of 10 that points to EX3
D. An MX record that has a preference value of 20 that points to EX3
