According to keynesian economics, which sector of the economy could offset a decline in business spending?

Government

Government plays a critical role in providing counter-cyclical demand management. Government spending can increase demand when there is a decline in private spending. This can be achieved through stimulus spending such as on infrastructure or the military. Government spending can help pull the economy from a slowdown.

both are true, the congress does have the power to create banks, even if this power is not specifically described in the constitution, since there is nothing restricting it and there is power given to the congress to make "all laws which shall be necessary and proper". maryland was not allowed to tax a branch of the national bank operating there, and the supreme court decided that no state could. both of these topics were discussed in a decision of the mcculloch v. maryland case in 1819.