What is a requirement for setting up R77 Management High Availability?

What is a requirement for setting up R77 Management High Availability?

A.
All Security Management Servers must reside in the same LAN.

B.
State synchronization must be enabled on the secondary Security Management Server.

C.
All Security Management Servers must have the same operating system.

D.
All Security Management Servers must have the same number of NICs.