The Text Tells Us That Early Evidence of Agriculture Appears

The text tells us that early evidence of agriculture appears in numerous places around the globe,including the Indus River in South Asia,the Yellow River in China,the Nile valley in Egypt and,of course,the Fertile Crescent region in Mesopotamia.Southern Africa is notably absent,and this may be because

A) egalitarianism was well established and there was little need to change that.
B) the population of that region was too small to support agriculture.
C) the poor conditions and soil precluded the use of cultivation.
D) that population was not intelligent enough to develop agriculture.