We need to know what the answer to #2 was first
The Allies learned their lesson from WWI by not punishing Germany too harshly. Instead, they focused on rebuilding Germany's infrastructure and economy and they also wanted to create the United Nations to be able to sort out conflicts between nations to prevent another war from happening
The early 20th century was an era of business expansion and progressive reform in the United States. The progressives, as they called themselves, worked to make American society a better and safer place in which to live. ... This generation of Americans also hoped to make the world a more democratic place.
The last one is correct.
Hope i helped!