Answer:
D. 900
Step-by-step explanation:
MPC = 0.90
The multiplier = MPC \ {1 - MPC} = 0.90 / (1-0.90) = 0.90 / 0.10 = 9
The Effect = Decrease in taxes * Spending multiplier
The Effect = $100 * 9
The Effect = $900
So, an decrease in taxes of $100 billion with an MPC of 0.90 will add a total of $900 billion to the economy after the multiplier effect.