Answer:
D.
Explanation:
The main reason for this is that the soil would wear out and could no longer support farming. If soil begins to wear out the plants will never grow or die out before reaching full maturity. If the Olmec farmers did not move from time to time their crops would not provide them with the necessary food in order to survive, therefore eventually starving. Their solution to this was moving to locations were the soil could better support their crops and provide larger harvests.