What factor led civilizations to develop a division of labor

The correct answer is D) food surpluses.

The factor that led civilizations to develop a division of labor was food surpluses.

When ancient civilizations stop being nomads to settle in some locations, basically next to the rivers, they had to farm the fields in order to get food and survive. They still hunt animals but most of them were dedicated to perfect agriculture. That is why the Sumerians settled in the middle of the Tigres and Euphrates Rivers, or the Egyptians, next to the Nile River. When they dominated agriculture and had food surpluses, humans started to do other things and new activities that made societies to improve.

The other options of the question were a) a written language, b) a small population size, and c) simple government structures.