Russian front ? What is the definition

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.

How did the invention of the cotton gin affect slave labor in the united states? a. there was a forced migration of slaves from the south to the north. b. slave-owning cotton planters were gradually forced to sell their plantations. c. more slaves were purchased to work on cotton plantations in the south. d. the reduced need for labor on cotton plantations led to a decline in slavery. e. slaves were moved from cotton plantations to sugar plantations.

Which of these is not a criticism of the concentric zone model? it does not accurately describe cities after the rise of suburban development. it only applies to cities that grew after the development of the automobile. it assumes that inner-city areas will always be repurposed instead of abandoned. it places too much importance on the traditional central business district.