Discuss which monetary policy is used most often and why.

The most frequently subscribed and implemented monetary policy instrument is open market operations. Open market operations involve the sale and purchase of government securities by the central bank in the open market to absorb or inject money into the economy, respectively. The interest rate targeted with open market operations is the federal funds rate, specifically.

The flexibility and ease of operations are the reason behind this monetary policy instrument's popularity. In simple terms, when the central bank wishes to increase (decrease) money supply under an expansionary (contractionary) measure, it purchases (sells) financial instruments, primarily government securities, and makes a deposit (withdraws funds from) in the account held at the central bank by the dealer. This increases (decreases) the commercial bank's credit creation capacity, which allows it to decrease (increase) its interest rates charged on loans. Consequently, money is injected (absorbed from) the economy due to the decreased (increased) cost of borrowing.

Other monetary policy tools are more uncertain in their potential outcome, such as quantitative easing, or are sticky in nature i.e. take time to show results.