Which of the following is a function of the Central Bank of Nigeria?

The function of the Central Bank of Nigeria (CBN) as a "banker's bank" means that it provides banking services to other banks and financial institutions in the country. This includes maintaining their accounts, providing loans and advances, and facilitating transactions between them. By acting as a banker's bank, the CBN helps to ensure the stability of the banking system in Nigeria. It also plays a key role in setting monetary policy, which involves controlling the money supply and interest rates to achieve macroeconomic objectives such as price stability, economic growth, and employment. Therefore, the correct option from the given list is "serving as banker's bank."