Explanation:

- Option 1: Burma

- Correct Answer

- The Reserve Bank of India (RBI) served as the central bank for Burma (now Myanmar) until April 1947. After this period, Burma established its own central bank.

- Option 2: Nepal

- The RBI does not act as a central bank for Nepal. Nepal has its own central bank, the Nepal Rastra Bank, established in 1956.

- Option 3: Bhutan

- The RBI is not the central bank for Bhutan. Bhutan's central bank is the Royal Monetary Authority of Bhutan, established in 1982.

- Option 4: Sri Lanka

- The RBI was never the central bank for Sri Lanka. The Central Bank of Sri Lanka was established in 1950.