Which three circumstances determine that some participants do not have video, but they do have audio?

During a conference that is hosted on a Cisco TelePresence Server, which three circumstances determine that some participants do not have video, but they do have audio? (Choose three.)
A. The participants have no video component.
B. No free screen licensing ports are available.
C. No video ports are available in a slave Cisco TelePresence Server configuration.
D. The maximum number of participants is exceeded.
E. In all Cisco TelePresence deployments, some participants are connected only via audio.
F. No video ports are available in a single Cisco TelePresence Server configuration.