Q.State Marshall's definition of Economics.

Economics has been defined in four major ways, each addressing a weakness in the one before it. Adam Smith's wealth definition treated Economics as the science of wealth — its production, exchange and distribution — but was criticised as narrow and materialistic. Alfred Marshall's welfare definition shifted the focus to mankind and material well-being, but Robbins criticised it for restricting Economics to only "material" welfare and for being merely classificatory rather than analytical. Lionel Robbins' scarcity definition made Economics the science of choice between unlimited ends and scarce means with alternative uses, giving it a universal and value-free character, but critics said it was too abstract and essentially microeconomic, ignoring aggregate problems like growth and employment. Paul Samuelson's growth-oriented definition synthesised all three — production/consumption of scarce resources having alternative uses, over time, with attention to costs and benefits of improving allocation — and is regarded as the most comprehensive modern definition.