Answer:
B) Slavery
Explanation:
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Answer:~At the center, information about tides and currents was collected, more accurate charts and maps were drawn, techniques for determining longitude were improved, and new ship designs (such as the caravel) were developed
 
        
                    
             
        
        
        
Answer:
d. They had different ideas about the ultimate power of the federal government.
Explanation:
 
        
             
        
        
        
From colonial times into the early 20th century a majority of americans lived in the countryside and worked on farms. A dramatic expansion in farming took place from 1860 yo 1910. The number of farms tripled from two million in 1860 to 6 million in 1905. The number of people living on farms grew from about 10 million in 1860 to 22 million in 1880 to 31 million in 1905. 
This means that the <em>cities at the end of the 19th century</em> were large because of the rural life. Although the eastern image of farm life on the prairies emphasizes the isolation of the lonely farmer and farm life, in reality rural folk created a rich social life for themselves.