Which part of a hybrid cloud-based deployment with Cisco Webex Messenger Service is used for meeting capabilities?

Which part of a hybrid cloud-based deployment with Cisco Webex Messenger Service is used for meeting capabilities?
A. Cisco Unified CM is always used for meeting capabilities.
B. Depending on the media flow, the Webex Meeting Center or local Cisco Unified CM meeting resources are used for meeting capabilities.
C. Depending on the origin of the user, the Webex Meeting Center or local Cisco Unified Communications Manager meeting resources are used for meeting capabilities.
D. Cisco Webex Meeting Center is always used for meeting capabilities.