The correct option is C RBI.
Reserve Bank of India(RBI) is an apex institution and bank that regulates and controls the entire banking system of India. It is the sole agency of issuing currency notes in the economy and controls the supply of money in the economy through its monetary policy. It serves as the
banker of the government and manages foreign exchange of the government. It is also known as the banker's bank because it acts as an agent, guide and bank to other commercial banks. Therefore, Reserve Bank of India(RBI) renders the function of a central bank in India.