Which component of civilization is essential to creating an environment that allows the others to develop? a building cities b surplus of food c dividing labor d location

i believe the answer is c

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."