Suppose the Economy Is Initially in Long-Run Equilibrium

Multiple Choice

Suppose the economy is initially in long-run equilibrium.Which of the following best describes the effects of a shift in aggregate demand?  

A)  Prices and output are affected in the short run and in the long run. 
B)  Prices and output are affected only in the short run. 
C)  Prices are affected in the long run and in the short run, but output is affected only in the short run. 
D)  Prices are affected in the long run and in the short run, but output is affected only in the long run.