Answer:
Option (c) is correct.
Step-by-step explanation:
Multiplier effect = 1 ÷ (1 - marginal propensity to consume) 
 = 1 ÷ (1 - 0.75) 
 = 4 
 Net exports = Exports - Imports
 = 0.5 - 0.7
 = (-0.2) 
 Impact on the equilibrium income = Net exports × Multiplier effect
 = (-0.2) × 4 
 = (-0.8), 
so, the equilibrium income will fall by $0.8 trillion.