If your possible answers are
economic
globalization, which led to high unemployment among the unskilled
sectors of the lower class
racial discrimination in hiring for the
remaining low-skilled jobs in urban centers
the cycle of poverty that
is reinforced among the poor
all of the above
Then the correct answer is all of the above. The cities started increasing in size and population and more and more people moved to them and since there wasn't enough jobs for everyone, or they were discriminated, they were poor which created entire neighborhoods famous for poverty.