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

All the give options were agricultural hearths except Sub-Saharan Africa.

Option B

Explanation:

Sub-Saharan is the area that is lying south of the desert named as Sahara and it is in the African continent. The land area that is used for the purpose of agriculture in this continent is 60% of the agricultural land in the world.  

This continent has very low crop yield output.  Farm to Market Alliance organizers say that the agricultural land in Africa is only six percent and it uses very less fertilizers than other countries in the world.  

the answer is blue river