Certkiller .com has a DL710 with two engines in place. An Implementation Engineer is onsite trying to configure Active Engine Failover, but is having no success. What is the problem?

A.
Active Engine Failover license is not installed

B.
Write cache is disabled

C.
The Active Engine Failover proxy agent is not installed on the backup server

D.
Active Engine Failover is not available on the DL710