The answer is: D. the amount of a good that is bought for a specific amount of money
The interaction made by sellers and buyers revolve around the trades of resources that they owned.
For example, let's say that you buy 10 donuts for 1$ each.
To complete the transaction, you need to give exactly $10 to the sellers (specific amount of money) and the sellers need to give you exactly 10 donuts (specific amount of goods) .
