Final answer:
The sole source of network television and local audience information in the United States is Nielsen Media Research. They offer critical audience ratings that help shape advertising rates and program popularity. This media measurement affects a vast number of television and radio stations across the country.
Step-by-step explanation:
The sole source of network television and local audience information in the United States is B. Nielsen Media Research. Nielsen's ratings are a pivotal tool for television stations to gauge the popularity of their shows and to set advertising rates based on the size of the audience. It's essential for the networks that produce a variety of content including news, public affairs, and sports programs. Most local stations are affiliated with national networks and broadcast this programming to local viewers.
Historically, in the United States, major networks like ABC, CBS, and NBC dominated television, but now there are more players in the field including PBS, the BBC, and Al Jazeera. Additionally, radio programming, although not the focus of this question, also has predominant companies like Westwood One providing content. It's interesting to note that six corporations, including the recently merged Viacom and CBS, control a significant percentage of the media in America, impacting the flow of information to the public.
Media conglomerates utilize various platforms such as local television, network television, cable, and satellite to distribute programming to audiences. With technological advances, viewers now have access to on-demand and streaming content, which changes the way advertisements are presented and schedules are planned.