The Traditional Definition of national income was proposed by Alfred Marshall, a renowned economist.

The correct answer for the economist who proposed the Traditional Definition of national income is option 'D', Alfred Marshall. Let's understand the concept of national income and Alfred Marshall's contribution to its definition.

National income refers to the total value of all goods and services produced within a country's borders in a specific time period, usually a year. It is an important economic indicator that helps in assessing the overall economic performance of a nation.

Alfred Marshall was a prominent economist of the late 19th and early 20th centuries. He made significant contributions to the field of economics, particularly in microeconomics and the study of markets. While he is best known for his work on supply and demand, Marshall also made important contributions to the measurement of national income.

Marshall's Definition of National Income:
Marshall proposed the Traditional Definition of national income, which was later refined and developed by other economists such as Simon Kuznets. Marshall's definition focused on the concept of net income, which is the difference between the total value of output produced and the cost of producing that output.

According to Marshall, national income is the net income generated by the productive activity of a country during a specific period. It includes the income earned by individuals, businesses, and the government through the production and sale of goods and services. Marshall emphasized the importance of deducting the costs of production from the total value of output to arrive at the net income figure.

Marshall's definition laid the foundation for the measurement of national income and provided a framework for understanding the economic activity of a country. However, it had limitations, such as not accounting for non-market activities, household production, and the distribution of income.

Further Developments:
Simon Kuznets, an American economist, further developed the concept of national income and introduced the concept of Gross National Product (GNP) in the 1930s. GNP includes not only the value of goods and services produced domestically but also the income earned by citizens abroad. Kuznets also introduced various adjustments to account for different types of economic activities.

In conclusion, Alfred Marshall, a renowned economist, proposed the Traditional Definition of national income. His definition focused on the concept of net income and provided a framework for measuring the economic activity of a country. However, it was later refined and developed by other economists such as Simon Kuznets to account for various factors and improve the accuracy of measurement.