What are the four tools of monetary policy

What are the four tools of monetary policy?
Tool one (150 words): How do these tools correct any deviation in the business cycle concerning unemployment and inflation?
Tool two (150 words): How do these tools balance out the lending and borrowing in the financial market?
Tool three (150 words): How do these tools help banking systems to borrow from one another and the Federal Reserve.
Tool four (150 words): How do these tools facilitate an investment activities:
During recession
During expansion

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