A car dealership sells 20 cars when there is a $2,000 markup over the factory price of each vehicle. The sales department determines that for each $400 decrease in markup an additional 6 cars are sold. Write a function that models the total monthly profit P(n). Let n represent the number of markdowns. A) P(n) = 2400n2 + 4000n + 40,000 B) P(n) = 2400n2 − 4000n + 40,000 C) P(n) = −2400n2 + 4000n + 40,000 D) P(n) = −2400n2 − 4000n + 40,000