Which one of the following statements regarding aggregate supply curves is correct?
Expansionary demand-side policies will always increase real national output when the economy is on the vertical section of the Keynesian long-run aggregate supply curve.
The classical long-run aggregate supply curve implies that any output gap will be automatically eliminated in the long run through price and wage flexibility.
The Keynesian long-run aggregate supply curve is perfectly inelastic at all levels of real national output.
The classical long-run aggregate supply curve suggests that long-run economic growth is determined solely by changes in aggregate demand.