The correct answer is C. remains constant
If production costs for both are equal, then it is completely the same what the demand is great for, since the cost will always be the same for them. If people want 3 cars and 2 trucks, it will be the same as if they wanted 4 trucks and 1 car.
Explanation:
it is a document given by the supplier,which contains
information on the quality,PRICE of goods sold
also date
well this is what ik,so hope it helps ig