Which option is a requirement for Cisco Unified Communications Manager clustering?

A.
Multiple servers run the exact same version of Cisco Unified Communications Manager.

B.
The Publisher runs the same or a newer version of Cisco Unified Communications Manager as
the Subscribers.

C.
The Subscribers run the same or a newer version of Cisco Unified Communications Manager
as the Publisher.

D.
Multiple servers run any version of Cisco Unified Communications Manager as long as they
belong to the same major release.

Explanation: