What is flat or rolling land with few changes in elevation

Which of the following best describes the economy of africa?

What's a recharge area? a. the part of an aquifer where groundwater meets a lake or stream b. the part of an aquifer where surface water reaches the water table c. the part of an aquifer that's located between two aquicludes d. the part of an aquifer that's located at a lower elevation

Indicates how many people live in an area