9.the poor soil of the sahel forces farmers to
a. clear new areas of land after a few years
b. expand their livestock herds
c. grow plants for forage
d. plant only cash crops

A.) Clear new areas of land after a few years

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d. stage 4

explanation:

the existence of some kind of demographic transition is widely accepted in the social sciences because of the well-established historical correlation linking dropping fertility to social and economic development.[1] scholars debate whether industrialization and higher incomes lead to lower population, or whether lower populations lead to industrialization and higher incomes. scholars also debate to what extent various proposed and sometimes inter-related factors such as higher per capita income,lower mortality, old-age security, and rise of demand for human capital are involved.[2]

tension is the type of stress that results when two tectonic plates diverge .

explanation: