When the central bank buys bonds, it injects high-powered money into the banking system. The initial deposit increases the bank's reserves. Through the fractional reserve banking system, the bank can lend out a portion of these reserves, leading to a multiple expansion of the total money supply, the magnitude of which is determined by the reserve requirement ratio.

Lower interest rates generally reduce the cost of borrowing, which incentivizes firms to invest and households to consume more. The provided answer 'B' states that lower interest rates increase the cost of borrowing, which contradicts the fundamental economic principle that lower rates make credit cheaper. This answer appears to be factually incorrect based on standard monetary theory.

Open Market Operations (OMO) refer to the buying and selling of government securities in the open market by a central bank. This is a primary tool of monetary policy used to regulate the money supply. When the central bank buys securities, it injects liquidity into the banking system; when it sells them, it absorbs liquidity, thereby influencing interest rates and economic activity.

A Treasury bill (T-bill) is a short-term debt obligation backed by the government with a maturity of less than one year. They are sold at a discount to their face value and do not pay interest; instead, the return is the difference between the purchase price and the face value received at maturity. They are essential tools for managing short-term liquidity in the economy.

Controlling the monetary base involves the central bank managing the total amount of high-powered money in the economy. A primary tool for this is the reserve requirement, which mandates that commercial banks hold a specific percentage of their deposit liabilities as reserves with the central bank. By adjusting these requirements, the central bank directly influences the liquidity available to the banking system and the overall money supply.

Expansionary monetary policy involves actions by the central bank, such as open market purchases of securities or lowering reserve requirements, to increase the money supply. By increasing the money supply, the central bank aims to lower interest rates, which encourages investment and consumption, ultimately leading to an increase in aggregate output and economic growth.

The Central Bank is the apex monetary authority responsible for managing a nation's money supply, interest rates, and credit conditions to achieve macroeconomic objectives such as price stability, full employment, and sustainable economic growth.

An expansionary monetary policy is designed to increase the money supply and stimulate economic activity. By purchasing government securities on the open market, the central bank injects liquidity into the banking system, which lowers interest rates and encourages borrowing and investment. Conversely, selling securities or raising reserve requirements would contract the money supply.

Treasury bills are short-term debt instruments issued by the government to manage temporary liquidity needs. They are sold at a discount and mature at face value, allowing the government to borrow funds for periods typically less than one year.

The term 'discount rate' has dual meanings. In commercial finance, it refers to the interest deducted in advance when discounting commercial paper. In macroeconomics, it refers to the interest rate charged by a central bank on loans provided to commercial banks, serving as a key tool of monetary policy.