In which areas of the United States did the Dust Bowl of the 1930's occur? a) Northeast
b) Southeast
c) Great Plains
d) Pacific Southwest

it occured in the great plains

Explanation:

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(202 bc - 220 ad) dynasty started by lui bang; a great and long-lasting rule, it discarded the harsh policies of the qin dynasty and adopted confucian principles; han rulers chose officials who passed the civil service exams rather than birth; it was a time of prosperity

porter is writing economic history because he is focusing on the cost of developing vaccines.