Please assist with the given problem.
Problem: Assume the government raises taxes by $20 billion and at the same time increases government spending by $20 billion. If the marginal propensity to consume (mpc) = 0.9 and everything else stays constant, according to the expenditure approach we can surmise that the level of income will:
a. increase by $200 billion
b. decrease by $200 billion
c. decrease by $20 billion
d. increase by $20 billion