Because the soil was depleted during the time of the dust bowl many people:

Moved westward to coastal states, is the right answer.

Explanation:

The Southern Plains experienced severe drought throughout the 1930's. Due to this relentless dust storms occurred that destroyed the ecology and farming of the prairies of America and Canada. Due to such climatic conditions, people and livestock died in Texas, Oklahoma and Nebraska. Since agricultural activities could not take place in such an environment thus people chose to move West in search of better living opportunities in the West Coastal region of the nation.

the first historical instance of china engaging in internationalism was during the han dynasty.[1] at the start of the han dynasty, the huns in the north were attacking the frontiers of han and trying to obtain riches. emperor wu of han wanted to gain an alliance with a country called dayuezhi so the two countries could join together and fight against the huns.[2] to obtain this alliance, emperor wu sent zhang qian to the west to establish economic and cultural connections.[2] history records that during the han dynasty there were four primary avenues of contact between china and europe. they included the northern land route, the central land route, the southern sea route, and the far southern sea route.[1] the most famous of these routes is the central land route, or the classical silk road, comprising a network of roads stretching from northwest china to the ports of syria and the black sea, which passed through the oasis of the turkestans and northern persia.[1] the silk road was significant for chinese emperors because it provided dominance over central asia by developing resources and provided new markets for the export of china's most valuable resources.[1]

b or c im pretty sure