Use the graph to answer the question that follows. LR' LR Inflation Rate U, U Unemployment Rate In the accompanying graph, the long-run Phillips curve has shifted from LR to LR'. Which of the following could explain this shift? O Expansionary fiscal policy that reduces unemployment and increases inflation A lower expected rate of inflation The economy moving, reaching full employment, with real GDP corresponding to long-run aggregate supply O More efficient labor markets that reduce frictional unemployment and the natural rate of unemployment An inward shift in short-run aggregate supply that increases cyclical unemployment