People in the south used slaves because their economy was focussed on things like cash crops (tobacco, cotton, etc.) These crops required a lot of work so farmers and plantation owners could not do it by themselves. So by using enslave persons they could harvest more crops, sell more, make more money, and in return boost the southern economy.
Answer:
The Soviet Union began to secretly install missiles in Cuba to launch attacks on U.S. cities
Explanation:
The Urban Areas were used to house these Immigrants and they grew larger.
Both implies two so your answer is two