Final answer:
After WWI, many people migrated to cities due to industrialization, some economies began to fail due to war costs and transitions, and there was an increase in the standard of living during the Boom years in the United States.
Step-by-step explanation:
World War I (WWI) had multiple significant outcomes that affected societies and economies worldwide. Among the results of WWI, we can identify that many migrated to cities as industrialization advanced, leading to urban growth. Concurrently, the war's end marked the beginning of economic challenges, with some economies beginning to falter due to the cost of war and the transition from wartime production to peacetime. Hence, it's accurate to state that the economy began to fail in many of the war-torn and participating countries due to these factors. Additionally, the period after WWI, specifically the 1920s, saw a surge in economic prosperity in countries such as the United States, which experienced what is often referred to as the Boom years. This era led to a rise in the standard of living for many, so it's reasonable to say that the standard of living increased for most in certain areas.