Some African countries' economies are negatively influenced by A. an overdependence on a single resource
B. an overdependence on a variety of natural resources
C. the lack of natural resources
D. an overdependence on industrial exports

A. an overdependence on a single resource

Explanation:

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.