8. In the AS-AD model, what is the difference between short-run and long-run equilibrium? a. In the short run, real GDP equals potential GDP; in the long run, the economy is always at full employment. b. In the short run, real GDP may deviate from potential GDP; in the long run, the economy returns to natural level of output. c. In the short run, the price level is fixed; in the long run, the price level is flexible. d. In the short run, there is no equilibrium; in the long run, the economy achieves equilibrium.