Explanation:

all are correct

Explanation:
The Reserve Bank of India (RBI) performs all the listed functions:

1. Regulator of Banks and Development Authority – RBI regulates the functioning of commercial banks and development financial institutions in India.
2. Regulator of NBFCs – It also regulates Non-Banking Financial Companies (NBFCs).
3. Lender of Last Resort – RBI provides financial assistance to banks and financial institutions facing liquidity crises.
4. Banker's Bank – It acts as the central bank for commercial banks in India, managing their cash reserves and clearing settlements.
5. Regulator of Open Market Operations – RBI conducts open market operations to control liquidity and stabilize the economy.