I need help with this question

American troops were worried about cantracting in cuba a. yellow fever b. hepatitis c. polio

The map makes it clear that after world war ii, korea was a a) part of china b) divided country c)part of japan d)unified country

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.