A farmer observes that the demand for corn, Q, in thousands of bushels per month, and price, P. in dollars per bushel, are related by a linear function. If a demand of 2,500 bushels per month corresponds to a price of $4.00 per bushel , and a demand of 3,000 bushels per month corresponds to a price of $3.20 per bushel, which of the following graphs represents the relationship between P and Q?