Determine the average rate of change, in gallons of gas per year, from 1960 and 1999 and then determine what the result means in this situation. a. -0.33gal/year; the average fuel consumption per year of a passenger car in the U.S. decreased by a third of a gallon per year. b. 0.33 gal/year; the average fuel consumption per year of a passenger car in the U.S. increased by a third of a gallon per year. c. 2.97 gal/year; the average fuel consumption per year of a passenger car in the U.S. increased by nearly 3 gal/year. d. -2.97 gal/year; the average fuel consumption per year of a passenger car in the U.S. decreased by nearly 3 gal/year.