Most countries in Africa south of the Sahara a. became independent during 1800s
b. became colonies during the
c. gained independence between 1950 the 1800s. and 2000.
d. joined in a single union of African 1950s and 1960s. states in 1999

What are the following resources?

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.