Explanation:

- Microfinance Institutions (MFIs) are regulated by the Reserve Bank of India (RBI).

- The RBI is the central bank of India and oversees banks and financial institutions, including MFIs.

- Option 1: SEBI (Securities and Exchange Board of India)

- SEBI regulates the securities market and protects investors. It does not regulate MFIs.

- Option 3: NABARD (National Bank for Agriculture and Rural Development)

- NABARD focuses on financing and promoting agriculture and rural development but does not regulate MFIs.

- Option 4: SBI (State Bank of India)

- SBI is a public sector bank and does not regulate other institutions or MFIs.