Answer:
d. the price the consumers are willing to pay for a roll of film
Step-by-step explanation:
The option āDā is correct because the supply curve is upward sloping and shows the positive relationship with the price mentioned on the verticle axis of the curve. This price is the same price that a person pays for the commodity. If the price paid by the person is more, then the supplier will supply more. If the price is lower, then the supplier will supply less. Thus, this shows that price and supply and positively related to each other.