Explanation:

Here’s the thing: the central bank doesn’t just use one method to control credit. Let’s break down each option:

- Bank Rate: This is the rate at which the central bank lends to commercial banks. Raising or lowering this rate can influence the overall cost of borrowing.

- Open Market Operations: Here, the central bank buys or sells government securities. Buying puts more money (credit) into the banking system, while selling pulls money out.

- CRR (Cash Reserve Ratio): Banks must keep a certain percentage of deposits with the central bank. If the central bank increases CRR, banks have less to lend out, so credit shrinks.

- All the above: The central bank actually uses *all* these tools, and often in combination, to control the amount of credit available in the economy.

Option 4: All the above is correct.