If a firm's marginal costs ________ then its ________

When economies of scale exist:

a. per unit production costs increase as output expands b. per unit production costs decline as output expands. c. marginal cost must decrease as output expands. d. per unit production costs remain constant as output expands.

The level of potential output and location of the long-run aggregate supply curve are determined by:

A. Federal Reserve policy. B. the price level. C. the intersection of aggregate demand and short-run aggregate supply. D. the natural rate of unemployment.