Read the passage carefully and answer the questions based on the passage:

Macroeconomics: Economy as a whole

The founding father of modern economics, had suggested that if the buyers and sellers in each market take their decisions following only their own self-interest, economists will not need to think of the wealth and welfare of the country as a whole separately. For various purposes macroeconomists had to study the effects in the markets of taxation and other budgetary policies, and policies for bringing about changes in money supply, the rate of interest, wages, employment, and output. Macroeconomics has, therefore, deep roots in microeconomics because it has to study the aggregate effects of the forces of demand and supply in the markets.

In a simplified economy, the households may dispose off their earnings by spending their entire income on the goods and services produced by the domestic firms as other channels if disposing their income are closed. The factors of production use their remunerations to buy the goods and services which they assisted in producing. The aggregate consumption by the households of the economy is equal to the aggregate expenditure on goods and services produced by the firms in the economy.

The decision of an individual economic agent is the study of ______.

Microeconomics

The correct answer is Option (3) → Microeconomics 

Microeconomics studies the behavior and decisions of individual economic agents such as consumers, producers, and firms. It focuses on how they make choices regarding what to produce, how much to produce, and at what price, as well as how these decisions interact in individual markets of goods and services.

In contrast, macroeconomics studies the economy as a whole — including aggregate demand, national income, inflation, and unemployment.