Final answer:
In the 1960s, ABC, CBS, and NBC were the three dominant networks in U.S. television news, competing for viewers and advertising revenue.
Step-by-step explanation:
The three networks that dominated television news in the 1960s were ABC (American Broadcasting Company), CBS (Columbia Broadcasting System), and NBC (National Broadcasting Company). These major networks were in fierce competition for viewership and advertising dollars, setting the stage for the way news was presented and consumed by the public. While there were also educational and nonprofit alternatives such as PBS (Public Broadcasting Service), the BBC (British Broadcasting Company), and CBC (Canadian Broadcasting Company), the bulk of mainstream American viewers received their news from the three dominant networks.