Another way to read history is to look for causes and effects as you read. What cause and effect relationship is suggested in this paragraph?

In 1920, the first commercial radio station went on the air to deliver election results. In 1924, radio allowed Americans to hear, for the first time, the proceedings of a national political convention. The popularity of radio spread quickly during the 1920’s. People all over the country could hear live concerts, dance music, sporting events, and news. Adventures series such as The Long Ranger were especially popular. Also during this time, daytime dramas (more serious stories that were continued from day to day) introduced a new kind of advertising—the corporate sponsor. The first sponsors were soap-making companies who offered to pay for the shows to be written, produced and played on air—as long as the station also suggested that listeners buy the soap! Today, both “soap operas,” as these shows were called, and commercial sponsors, continue as a prominent feature of American life.

a.Adventure series like The Lone Ranger were the effect of new approaches to advertising.
b.The rise and popularity of radio caused a new approach to advertising.
c.The use of commercial sponsors was caused by the use of radio to carry election results.
d.One effect of political conventions was the use of radio to broadcast them.