They used supply and demand and traded very many things
The correct answer to number 9 is B) Congressional re-election limitations.
The amount of terms the president can serve is limited by the 22nd amendment. The ability of 18 year to vote in US elections is guaranteed in the 26th amendment. The federal income tax is in the US Constitution as well, and it is the 16th amendment.
The correct answer to number 10 is C) Woman's ability to vote.
Women gained the right to vote thanks to the 19th amendment.
Well, European countries didn't exactly solved all the problems they had when WW1 ended. The only reason why WW1 ended was because Europe got tired of fighting and wanted to clean up the aftermath of war. And Germany was also in devastation after WW1 and Hitler blamed all of this to the Jews which led to WW2.
Technology is making people lazy