Answer:
The correct answer is A. Trade food for specialty items.
Step-by-step explanation:
As early civilizations' agriculture began to grow as a result of the advances in the farming technology like for example the irrigation system the production of food from crops sky rocketed, therefore less farmers where needed to supply the city food stock, as less farmers where needed, a lot of citizens began working in other jobs, like for example weavers, potters, merchants, leatherworkers. Farmers then began to trade this surpluses for things they could not produce but a potter could or a weaver as a result of the social phenomenom mentioned above.