Which invention encouraged tourism and created new businesses in the 1920s

During the early neolithic era, people relied on domesticated animals to provide each of the following except a. hides for clothes b. labor to pull plows c. manure for the soil d. meat, cheese, and milk for food

Nationalsim led to major conflicts following world war1 especially when

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.