People prefer IP phone calls to ordinary ones because the former is ______.

A．With VoIP technology, the phone caller's voice will be broken into pieces.
B．Different types of technology are accompanied with different advantages.
C．With VoIP technology, the quality of voice will always remain the same.
D．On the Internet, information will be broken into pieces and then connected again.

A．to introduce a new technology called VoIP
B．to inform that IP phone calls are sometimes quite awful
C．to tell us that IP calls are dependent on personal computers
D．to compare the IP calls with the traditional phone calls