Concept:Monetary policy is the central bank's strategy to control the supply of money and credit in the economy.
Explanation:Bank rate, cash ratio and open market operations are key instruments used by the central bank.
Bank rate is the rate at which the central bank lends money to commercial banks.
Cash ratio is the portion of deposits that banks must keep as reserves with the central bank.
Open market operations involve buying and selling government securities to regulate money supply.
All these tools directly influence the availability and cost of money in the economy.
Therefore, their combined use constitutes monetary policy, not fiscal, export or import policy.
Answer:A. monetary policy