Concept:Credit ceiling is a monetary policy instrument used to limit the maximum amount of credit banks can create.Explanation:The central bank uses credit ceiling to fix the total credit that commercial and merchant banks may give to the domestic economy.This limit directly controls the supply of money and helps to check inflation.Monetary policy is the broad framework, while fiscal policy deals with government spending and taxation.Open market operation involves buying and selling government securities, not fixing credit limits.Thus, the correct instrument is credit ceiling.Answer:C. credit ceiling