Explanation:

- The Reserve Bank of India (RBI) has set guidelines for appointing a Chief Compliance Officer (CCO) in banks.

- These guidelines aim to ensure stability and consistency in compliance functions.

- ?? Option 4: 3 years is the correct answer. The minimum tenure for a CCO, as stipulated by the RBI, should be 3 years.

- Other options such as 1, 2, 2.5, and 5 years are incorrect as per these specific guidelines.

- A stable tenure helps the CCO implement long-term compliance strategies effectively.