Industrial development in the North of the United States, combined with the mechanization of agriculture in the South, produced a progressive movement of northward starting at the beginning of the twentieth century.

African Americans

Explanation:

In the middle of the century, northern manufacturing extended the use of power-driven machines to a wider range of commodities. Agricultural mechanization throughout the 20th century led to dramatic shifts in farming. Tractors, combines, harvesters, and other farming equipment are helping farmers grow more.

Orogressive movement of Africans Americans northward starting at the beginning of the twentieth century was a result of economic boom in the this areas, they had to migrate and find jobs that can feed them and their families.

a and c?

i think it is a and c