Marginal utility approach was given by Alfred Marshall.

Explanation:

Marginal utility approach is a theory of economics that explains the relationship between the marginal utility of a good or service and the quantity of that good or service that is consumed. It was first introduced by Alfred Marshall in his book "Principles of Economics" published in 1890.

Marshall's theory of marginal utility emphasized the importance of the concept of diminishing marginal utility. According to this concept, the more of a particular good or service a person consumes, the less satisfaction or utility they will derive from each additional unit of that good or service.

Marshall believed that consumers make rational decisions about how much of a particular good or service to consume based on the marginal utility they derive from each unit of that good or service. In other words, consumers will continue to consume a good or service up to the point where the marginal utility they derive from each additional unit is equal to the price they pay for that unit.

Marshall's theory of marginal utility has been highly influential in the development of modern economic theory, particularly in the fields of microeconomics and consumer behavior. It has also been widely applied in practical contexts, such as the analysis of consumer demand and the pricing of goods and services.

In conclusion, Alfred Marshall was the economist who introduced the marginal utility approach, which has become a fundamental concept in modern economic theory.