Which of the following was a factor behind the shift from room-based hardware to PC-based software ?

Which of the following was a factor behind the shift from room-based hardware to PC-based software ?

A.
smaller footprint

B.
increase in CPU power

C.
CD-ROM as a medium

D.
availability of inexpensive webcams

Explanation:
http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND_40/QoSIntro_40.html

On the interactive video side of the video application hemisphere, there has also been considerable application evolution. Basic video conferencing applications, which were initially dedicated room-based units, evolved into software-based PC applications. The factors behind this shift from room-based hardware to PC-based software were two-fold:

The convenience of immediate desktop collaboration (rather than having to book or hunt for an available video-conferencing enabled room).

The availability of inexpensive Webcams. Desktop video conferencing may be utilized on a one-to-one basis or may support a few participants simultaneously.