Q.Which theory is generally included under Micro economics ?

The book 'Wealth of Nations' (1776) was written by Adam Smith, so the answer is option (d).

In the Tamil Nadu HSC Class-11 Economics syllabus, the growth of economic thought is introduced through the major definitions of economics. Each definition is tied to an economist:

• Adam Smith — the wealth definition, given in his 1776 book 'An Inquiry into the Nature and Causes of the Wealth of Nations'. He is called the Father of Economics.
• Alfred Marshall — the welfare definition ('Principles of Economics', 1890). …

Micro economics is also called Price Theory, so the answer is option (b).

Micro economics studies the economic behaviour of individual units — a single consumer, a single firm, a single industry — and focuses on how the prices of commodities and of factors of production are determined. Because price determination is its central concern, micro economics is popularly called Price Theory.

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"An Inquiry into the Nature and Causes of the Wealth of Nations" was written by Adam Smith.

Published in 1776, this book laid the foundation of modern economics with its "wealth" definition of the subject; its author Adam Smith is called the Father of Economics. The other names — Lionel Robbins (scarcity definition), Alfred Marshall (welfare definition) and Paul A. Samuelson (growth definition) — are associated with later definitions of economics, not with this boo …

'Economics is a study of mankind in the ordinary business of life' was stated by Alfred Marshall.

Alfred Marshall gave the welfare definition of economics, describing it as "a study of mankind in the ordinary business of life" — that is, the study of how people earn and use income to satisfy wants for material welfare. Adam Smith gave the wealth definition, Lionel Robbins …

The correct option is (c) Adam Smith, the Scottish economist whose 'Wealth of Nations' (1776) founded the modern study of Economics.

Economics as a systematic body of knowledge began with Adam Smith. In 1776 he published 'An Enquiry into the Nature and Causes of the Wealth of Nations', which analysed how wealth is produced, exchanged and distributed and gave the discipline its first coherent framework. For this reason he is universally called the Father of Economics.

Why the other options are wrong:

• (a) Paul A. Samuelson wrote a famous textbook and won the Nobel Prize, but he is a modern economist, not the founder. …