If Investment Decreases by $20 Billion and the Economy's MPC

Multiple Choice

If investment decreases by $20 billion and the economy's MPC is 0.5, the aggregate demand curve will shift

A) leftward by $40 billion at each price level.
B) rightward by $20 billion at each price level.
C) rightward by $40 billion at each price level.
D) leftward by $20 billion at each price level.