Final answer:
Marshall's definition of economics centers on enhancing the well-being of individuals and society by examining various aspects such as environmental impact, education, corporate and union activities, and government policies.
Step-by-step explanation:
The main features of Marshall's definition of economics as a social welfare discipline emphasize how it seeks to improve the well-being of all people. This includes considerations of those with various income levels and employment statuses. Marshall's view integrates Utilitarianism, which is a theory focused on maximizing happiness and well-being. In this context, economics addresses issues such as environmental pollution from production, the role of education in worker skill development, the consequences of actions by big businesses and labor unions, and the impacts of government spending, taxes, and regulations on production and consumption choices. These aspects highlight the multifaceted relationship between economic activities, society, and individual welfare.