Detailed Solution:
Money fundamentally solves the problem of the double coincidence of wants (barter system) by serving as a Medium of Exchange. Over time, it must maintain its purchasing power, making it a Store of Wealth (or Value). Furthermore, all goods and services are priced in terms of money, establishing it as the standard Unit of Account. Thus, A, B, and C are all core primary functions of money.

Detailed Solution:
Inflation is technically defined as a sustained and generalized upward movement in the overall price level of goods and services in an economy over a period of time. This inversely correlates with the purchasing power of money (as prices rise, money buys less). Options A and B define Deflation, and Option D implies Price Stability.

Detailed Solution:
Commercial banks interact directly with the general public, taking deposits and giving out retail and commercial loans. In contrast:
- Central banks deal with government monetary policy and regulate other banks.
- Investment banks deal with capital markets and corporate finance.
- Development banks fund long-term infrastructure and industrial projects.

Detailed Solution:
Monetary policy is controlled by the Central Bank to manage the money supply. Open Market Operations (OMO)—the buying and selling of government securities to influence liquidity—is a primary tool of monetary policy. Options A and B (Taxation and Public Expenditure) are tools of Fiscal Policy, managed by the government.

Detailed Solution:
An indirect tax is one where the incidence (the burden of the tax) is passed on to the final consumer, even though it is collected by an intermediary (like a retailer). GST is levied on the consumption of goods and services, making it a classic example of an indirect tax. Conversely, Income Tax is a direct tax because the entity earning the income pays it directly to the government.

Detailed Solution:
1. Nature of Money:
Money is defined as any universally accepted asset that serves in the settlement of debts and the exchange of goods and services. Its nature is characterized by general acceptability, portability, durability, divisibility, and uniformity. By having a legal tender status backed by a central authority, it facilitates frictionless trade.

2. Primary Functions of Money:

• Medium of Exchange:
  This is the most critical function of money. Before money, societies relied on the Barter System, which required a "double coincidence of wants" (e.g., a shoemaker wanting wheat must find a farmer wanting shoes). Money removes this friction. A person can sell goods for money and use that money to buy entirely different goods from a third party. It acts as a universal intermediary.


• Unit of Account (Measure of Value):
  Money acts as a common denominator to measure the value of diverse goods and services. Instead of pricing a cow in terms of dozens of apples or kilos of wheat, all goods are priced in a standard unit (e.g., Rupees, Dollars). This allows for macroeconomic accounting, calculation of profits/losses, and national income estimation.


• Store of Value:
  Unlike perishable goods (like fruits or grains), money can be saved and retrieved in the future without losing its fundamental utility. This allows individuals to shift purchasing power from the present to the future. A reliable store of value is essential for the creation of savings and investment ecosystems in an economy.

Detailed Solution:
1. Role and Core Functions of the Central Bank:
The Central Bank (e.g., RBI in India, Federal Reserve in the US) is the apex financial institution responsible for overseeing a nation's monetary system. Its primary functions include:

• Issuer of Currency: It holds the monopoly on issuing fiat currency notes, ensuring uniformity in the monetary system.
• Banker to the Government: It manages government accounts, facilitates public debt, and provides short-term advances to the government.
• Banker's Bank and Lender of Last Resort: It regulates commercial banks, holds their cash reserves, and provides emergency liquidity during financial panics to prevent bank runs.
• Custodian of Foreign Exchange Reserves: It manages national forex reserves to stabilize the external value of the domestic currency.

2. Controlling Inflation and Money Supply (Monetary Policy):
The central bank uses Monetary Policy tools to expand (expansionary) or contract (contractionary) the money supply to manage inflation. During high inflation, it applies a contractionary policy using the following tools:

• Bank Rate / Repo Rate Adjustment: By increasing the Repo Rate (the rate at which it lends to commercial banks), borrowing becomes expensive. Banks pass this high cost to consumers via higher loan interest rates. This discourages borrowing, reduces consumer spending and investment, thereby cooling down inflation.
• Open Market Operations (OMO): The central bank actively sells government securities in the open market. Commercial banks and the public buy these securities, transferring their cash liquidity to the central bank. This drains excess money from the economy.
• Cash Reserve Ratio (CRR): The central bank mandates that commercial banks keep a certain percentage of their deposits as cash reserves with the central bank. By raising the CRR, banks have less capital available to loan out, instantly reducing the credit creation capacity and shrinking the money supply.