4. Shifts in production possibilities Drag the production possibilities frontier (PPF) on the graph to show the effects of a long drought that reduces the amount of water available for farmers to use for irrigation. Note: Select either end of the curve on the graph to make the endpoints appear. Then drag one or both endpoints to the desired position. Points will snap into position, so if you try to move a point and it snaps back to its original position, just drag it a little farther. 120 a} 100 PPF 80 40 LOCOMOTIVES (Thousands) 20 PPF 0 60 120 180 240 300 360 BARLEY (Millions of bushels)