4. Why did farming spread into West Africa?

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Explanation:

Fueled by high population growth and a growing demand for food, agricultural expansion accounts for most land cover change across West Africa. ... Niger's vast south-central agricultural zone, already heavily cultivated in 1975, became fully saturated with cropland and expanded eastward into the pastoral zone.

he risk-return relationship. generally, the higher the potential return of an investment, the higher the risk. there is no guarantee that you will actually get a higher return by accepting more risk. diversification enables you to reduce the risk of your portfolio without sacrificing potential returns.

explanation: