Which of the following is NOT a type of economic system?

The answer is C, as an "Environmental economy" is not recognized as a distinct type of economic system. Economic systems are typically categorized into several well-defined types based on how they manage resources and distribute goods and services. Traditional economies rely on customs and traditions, command economies are controlled by centralized authorities, and market economies operate on supply and demand with minimal government intervention. In contrast, an environmental economy focuses on the relationship between economic activity and environmental sustainability but does not function as a standalone economic system like the others listed. This distinction clarifies why "Environmental economy" is not considered a type of economic system.