[ 421 ] Geography and the World GED ® TEST SOCIAL STUDIES FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • _____________ • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • For what purpose was the Great Wall of China most likely built? a. to provide protection from military invaders from the north b. to provide protection from military invaders from the south c. to create a tourist attraction that would bring international travelers to China d. to protect Beijing from flooding rivers Read the passage and answer the following two questions. The Aztec empire of the thirteenth and fourteenth centuries was based on an agricultural economy. The Valley of Mexico—a fertile basin with five lakes in its center—provided land for farming. However, as the population of the empire grew, the Aztecs needed to make more land suitable for agriculture. To do this, they developed irrigation (a system that carries water through dams and canals to use for farming) and formed terraces (a process that cuts “steps” into hillsides to make flat surfaces for farming). They also practiced land reclamation, turning swamps and wet areas into land that can be cultivated. What factor caused the Aztecs to develop agricultural innovations? a. The empire shifted from an agriculture-based economy to an industrial one. b. Annual flooding created rich soil, but the lakes could not sustain crops the rest of the year. c. An increase in population created a need for land for more housing. d. A growing population resulted in increased food demands.