Most people in africa who farm or herd for a living do it at the subsistence level. this means that a. they produce most of their crop or livestock for export to other countries b. they earn more than the national average, and they can afford to live in nice homes and buy all they need to survive c. they produce only enough to feed their family, and they have little left over to sell at a market d. they produce goods that are sold for cash, and they buy all of their food and other things needed to survive (its c.)

C:

Explanation:

A: That would make them wealthy. It's not the answer. They are poor.

B: They don't earn more than the national average. Subsistence means just enough to get by.

C: The answer. They are poor. They have just enough to keep alive. Nothing more at all.

D: They don't have enough to take to market.

a mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. this uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.a geomagnetic reversal is a change in a planet's magnetic field such that the positions of magnetic north and magnetic south are interchanged.