Answer:
The correct answer is the second option: respond to prices; determines the price.
So the final statement will be:
The demand and supply curves show how buyers and sellers respond to prices; the interaction of buyers and sellers determines the price.
Step-by-step explanation:
To begin with, in the microeconomics theory both the demand and supply curves are economic functions that are represented in the graphic in order to give a better understanding of what is going on in the reality of the economy out there. So that means that they are both determine by the quantity demanded or supplied and the price, the relation between those two components. And regarding that, they both will show how the buyers and sellers respond to prices. Moreover, their interaction will determine the price as explained before.