Consider the work done by a force. > 33% Part (a) in which of the following situations does the force in question do positive work? Check all that apply.a. The frictional force slows a car as it skids to a stop. b.The normal force pushes upward on Jean as she rides an escalator to a higher floor at the mallc. A rock falls to the ground under the influence of the gravitational force. d. The towrope exerts a force on a water skier who is towed behind a speedboat. Emily pulls upward on her briefcase to support it as she stands at the bus stop, waiting for the bus to arrive. e. The normal force pushes upward on a bicycle as it rides over horizontal ground. f. The gravitational force on a bus is directed downward as the bus moves over a horizontal road. g. A batted baseball is slowed by the gravitational force as it rises into the air. h. A block slides down an inclined plane, and the normal force is perpendicular to the plane