What means population per area such as number of people per square mile in a state

The african continent is home of the worlds largest desert and longest river . t or f

People keep spending additional units of a particular resource on a want until their marginal benefit is  decreasing withgreater thanless thannot affected by  their marginal cost.

Dubai is challenged by all of the following environmental factors except a. a warm and dry climate b. a lack of annual rainfall c. scarce freshwater resources d. a lack of valuable natural resources