How did the authorization of greenback bank notes affect the monetary system? a)

How did the authorization of greenback bank notes affect the monetary system?
a) It enabled a form of currency that could be used in both the North and
the South.
b) The declaration that greenbacks were legal tender enabled a solid
monetary system that outlasted the war.
c) It allowed for war profiteering at higher levels than ever before.
d) The authorization of greenbacks made the financial system more
unstable