How did the social trends of the 1920s impact the economy of the 1930s?

Look at this photograph taken during the battle of guadalcanal

1. why didnt the league of nations(lon) stop germany and italy from being aggressive towards other nations before the war? a. the lon supported german and italian aggression b. the lon was only concerned about japanese aggression c. the lon didnt have an army or real power to enforce what it wanted d. the lon was busy solving the spanish civil war2. why did allied powers try to appease nazi germany before ww11? a. all the following were reasons for appeasement b. world war 1 was so terrible that many leaders never wanted another war c. many people thought the newly-streangthened soviet union was a bigger threatd. many leaders wondered if they could win another war or if their old allies (like america) would even join their side this time 3. at the end of the war what 2 countrys emerged as global superpowers? (2) a. the united states b. great britain c. france d. the union of soviet socialist republics e. germany

Why were inventors essential or necessary for an industrial revolution to happen in america