What are the three major tools of Monetary Policy. What are those tools? Which one is the most powerful?

Question

What are the three major tools of Monetary Policy. What are those tools? Which one is the most powerful?

Answer 1

Monetary base/Bonds -  The central bank can control the circulation of money through the buying and selling of bonds.

If they want to reduce the amount of money circulating then they sell bonds (which are actually pieces of paper) in return for currency/money.They are not allowed to withdraw money.In return they get a really High Interest Rate on their money.

Reserve requirements Rate -  This is the minimum amount of money that central bank requires commercial banks to have in their reserves. This changes the availability of loanable funds. If it high then the supply of money will be low and vice versa.

Discount window lending -  This is in the US so I'm not so sure.

Interest rates/Discount Rate - I think this is like the interest rate that the central bank has on the commercial bank.

I'm not sure which is the most powerful. I guess its how effective each one is in each circumstance.