Federal government budget deficits

are good during recessions but ultimately require higher taxation in the future to bring the budget back towards balance.
are good during recessions because they put money into bank reserves in exchange for longer-maturing bonds.
are good during recessions because provide direct stimulus to the spending stream and finance private savings.
are good during recessions but need to be increased with caution because they increase the public borrowing requirement.

Answer: are good during recessions because provide direct stimulus to the spending stream and finance private savings.

Please see Deficit spending 101 - Part 1 if you are still wondering why the correct answer is three.