If congress decides to reduce the tax per pack paid by sellers of cigarettes, other things being equal, the equilibrium price of cigarettes will fall. this fall in the equilibrium price can be attributed to a(n):

The rise of advertising in the 1920s. i am good with seeing how advertisements shape the roaring twenties and how it developed a new way of life through modern days. but i am not sure what the details of advertising in the 1920s were. if possible can you send me links (preferrably credential links) to sources that maybe show like the first company to start advertising through the radio, how advertising benefits (statistics graphs), etc.