The simplest teleconference,available on most public and private phones,is:

A) web conferencing.
B) two-way radio system.
C) online meetings.
D) three-way calling.

Teleconference

A meeting of people in different locations using telecommunications devices such as telephones or computer networks to communicate.

Three-Way Calling

A feature offered by telephone service providers that allows three parties to speak to each other simultaneously on one phone call.