问题：

[单选] Telepresence and video conferencing have been an increasingly important component of the overall collaboration marker, which indicator is the best measure of the continued importance of these technologies going forward?（）

A . the annual growth rate of the video-conferencing market is 23 percent
B . generationY ,raised on video, comprises 17 percent of the world population
C . thecisco long-term growth-rate target is 12 percent to 17 percent
D . the U.S internet traffic annual growth rate is more than 40 percent