The main reason why the twenties are sometimes called an "age of prosperity", especially in the United States, is that "<span>A.Incomes throughout the United States grew and the middle class held most of the wealth," due mostly to speculation in the stock market. </span>
During this era, human technology boomed. In this era, nomads have started farming. Nomads have stopped moving from one place to another. They have started forging metal tools. They also started pastoralism. They have communities and tribe. They were able to create a system on their own.
it didnt apply to border staates but the answer to your test question is A to free all free all slaves.
(The lack of food) hope this helps :/