Get the information you need with the help of IDNLearn.com's expert community. Join our community to receive prompt and reliable responses to your questions from knowledgeable professionals.
Answer:
D. Paper money
Explanation:
We can eliminate option C because it was their main source of currency. Trade is used to import goods from other places, an important factor to the community. The barter system was a common way of paying or trade, so the same goes for option A.
Let me know if this is correct :)