The answer is D: television.
After the end of World War II, the television became widely marketed and it became a commonplace item in most households in the most industrialized countries, like the USA. By the 1950´s, the television was the primary means of broadcasting and the most relevant of tools when it came to influencing the opinion and tastes of the public, which, coupled with an economic boom in post-war USA, highly increased the consumer demands of the public.