Use the Following to Answer Questions

Multiple Choice

Use the following to answer questions .
Exhibit: Using the Aggregate Demand/Aggregate Supply Model 1
-(Exhibit: Using the Aggregate Demand/Aggregate Supply Model 1) Suppose the economy is initially in short-run equilibrium at B. A shift from AD₁ to AD₂ could have been caused by all of the following except

A) an increase in consumer optimism.
B) economic prosperity in foreign economies.
C) a personal income tax cut.
D) an increase in the price level from P_a to P_b.