Which of the following is NOT considered an economic system?

Monopoly is not considered an economic system like capitalism, socialism, or communism. Instead, a monopoly refers to a market structure in which a single seller or provider dominates the market for a particular good or service, leading to limited competition. This situation can arise within various economic systems, such as capitalism, where businesses operate freely in a competitive market. In contrast, capitalism, socialism, and communism are overarching frameworks that define how an economy is structured and operates, including how resources are allocated and managed. Thus, while capitalism, socialism, and communism all describe broader economic systems with specific characteristics related to ownership and distribution of resources, monopoly is a concept that describes a particular scenario within those systems.