When would sunk costs be irrelevant for current decision making?

You are given the following information about aggregate demand at the existing price level for an economy: (1) consumption = $400 billion, (2) investment = $40 billion, (3) government purchases = $90 billion, and (4) net export = $25 billion. if the full-employment level of gdp for this economy is $600 billion, then what combination of actions would be most consistent with closing the gdp gap here?