d. there were no divisions in communities of age and gender
Hunter-gatherer societies were nomadic, and lacked the expertise and technological progress to develop tools or to control fire.
They had to feed from and to use the resources they could find in the nature. This is why they were experts in animals and plants and they knew plenty of techniques related to hunting or fishing, for example, with almost no tools. They were mostly small groups and very united communities, as everybody's effort was necessary to reach common goals.
