Answer:
D. Southern states were readmitted into the Union after agreeing to several new amendments.
Explanation:
After the Civil War ended, slavery was prohibited in the United States, and over 4 million of former enslaved African Americans became free.
However, most of them were still poor and had little means to provide for their families. Thus, many of them became sharecroppers: they were allowed to use the land of a rich owner, in exchange for a part of the harvest.
As we can see, this system was very close to European feudalism of the Middle Ages. Which is to say that the end of slavery did not mean that the economic and social position of African Americans improved by a lot.
