If a central bank wants to curb inflation by tightening monetary policy, which of the following actions would it most likely take?

If a central bank wants to curb inflation by tightening monetary policy, which of the following actions would it most likely take?

1. a) Increase the policy (repo) rate
2. b) Lower the Cash Reserve Ratio (CRR)
3. c) Reduce the Statutory Liquidity Ratio (SLR)
4. d) Purchase government securities in the open market