The correct answer is C.
The accumulation of production surplus and the incipient trade activities among human communities during the Neolithic era, fostered job division and specialization. Different people were in charge of the different economic activities: hunting, gathering, animal husbandry, agriculture, fabrication of tools, etc.
Some economic activities started to be more highly valued. People were willing to give up a larger quantity of their posessions for obtaining, through a barter agreement, a craft knife than for example to obtain recolected fruits. Differently rewarded activities gave rise to the existence of income inequalities within the members of the neolithic socities.