The gas mileage for Kevin's car varies, depending on driving conditions. When driving on dirt roads, his average miles per hour are much less than when driving in a residential area. Kevin gets the best gas mileage when driving on a highway. To go to work, Kevin leaves his house and drives along a dirt road for approximately a quarter of the total distance from his home to work. Then he arrives in a residential area where he drives approximately half the total distance. Finally, he drives along a dirt road for an eighth of the total distance until he reaches the highway to complete his trip. Which graph best models the amount of gas in Kevin s gas tank during his drive to work?