Which mechanism does the Cisco TelePresence Conductor use to communicate with the call control device?

Which mechanism does the Cisco TelePresence Conductor use to communicate with the
call control device?

A.
A SIP connection will use the B2BUA of Cisco TelePresence Conductor.

B.
When Cisco TelePresence Conductor receives the signaling for the call, it uses CPL.

C.
It sends keepalive messages until the H.245 negotiations are completed.

D.
It provides a secure FTP channel to use for data transfer.