What is the main difference between Keynesian and supply-side fiscal policy? a.Keynesian policy increases incomes for middle-income households and supply-side policy increases incomes for upper-income households b.Keynesian policy increases the marginal propensity to consume for middle-income households and supply-side policy decreases the marginal propensity to consume for upper-income households c.Keynesian policy decreases incomes for upper-income households and supply-side policy increases incomes for upper-income households d.Keynesian policy increases taxes for upper-income households and supply-side policy increases taxes for upper-income households