All of the following were agricultural hearths, except
a.
mesopotamia
b.
sub-saharan africa
c.
the nile river valley
d.
mesoamerica

B. sub-Saharan Africa

Explanation:

The agricultural hearths were located along the Nile River, Mesopotamia, Hindus and Ganges Rivers, Mesoamerica, which is also where the first civilizations formed. Sub-Saharan Africa though was not keeping the pace with these regions, and the people living there were either not engaging in agriculture at all, or it was on a very small scale. That has led to a much slower development of this region, stagnating for thousands of years, eventually putting in a very bad situation when it confronted with the more developed civilizations later on in the history. One of the major reasons for not developing a large scale agricultural production has been the climate, which in the majority of the region is not well suited for such activity.