Which of the following is a monopoly market?

Answer
D. A market with a single seller, for a product with no close substitutes
Explanation
A monopoly market is characterized by a single seller who has complete control over the production and pricing of a particular product or service. In this type of market, there are no close substitutes for the product or service being offered. This means that consumers have no other options but to purchase the product or service from the monopolistic seller.
A monopoly market is often associated with high barriers to entry, which prevent new firms from entering the market and competing with the monopolistic seller. These barriers can include factors such as high startup costs, government regulations, or exclusive access to key resources or technology.
An example of a monopoly market is the U.S. Steel industry. U.S. Steel is a single seller that engages in the manufacturing and sale of steel products. The company has a significant market share, and there are no close substitutes for the steel products it produces. U.S. Steel has also been able to maintain its dominant position in the market by using its resources and technology to create barriers to entry for new firms.
Overall, a monopoly market is characterized by a single seller who has complete control over the production and pricing of a particular product or service. This market structure can have significant impacts on consumers, as prices may be higher and innovation and competition may be limited.