Correct Answer: Alfred Marshall.

Solution : The correct answer is (c) Alfred Marshall.

Alfred Marshall, a prominent economist of the late 19th and early 20th centuries, is credited with introducing the concept of elasticity. In his influential work "Principles of Economics" published in 1890, Marshall extensively discussed the concept of elasticity and its application to the analysis of supply and demand.

Marshall's work laid the foundation for modern microeconomic theory and greatly contributed to the understanding of how changes in price, income, and other factors affect the quantity demanded and supplied of goods and services. The concept of elasticity has since become a fundamental tool in economic analysis and decision-making.

While Adam Smith, Karl Marx, and John Maynard Keynes are notable economists who made significant contributions to the field of economics, the concept of elasticity was specifically introduced by Alfred Marshall.