While Fossil Fuel Consumption is often thought of when considering the efficiency of a Furnace, a secondary consideration of electrical consumption is also a consideration as the Air Handler's Blower Fan can consume substantial amounts of electricity over a heating season. There has been an evolution of improved performance in the motors that drive the Blower Fans. Which of the following choices places the motors in order of highest to lowest energy consumption per unit of time? Select one: a. Variable Speed Fan, Two Stage Fan, Single Stage Fan. b. Variable Speed Fan, Single Stage Fan, Two Stage Fan. c. Two Stage Fan, Single Stage Fan, Variable Speed Fan. d. Single Stage Fan, Two Stage Fan, Three Stage Fan e. Single Stage Fan, Variable Speed Fan, Two Stage Fan f. Single Stage Fan, Two Stage Fan, Variable Speed Fan