Families on the large farms kept in touch with each other by ______.

A．Most of Australia is too dry for people to live in and it is the same with the USA.
B．Some of the Australian farms are very large.
C．The people on the farms don’t have neighbors because they live far away from each other.
D．The Australian children don't like to go to school at all.

A．the radio has two telephones
B．you can talk to and listen to somebody by radio
C．the boys and girls can listen to somebody by radio
D．people can talk to a doctor hundreds of miles away by radio