Answer:
c. a pure monopoly.
Explanation:
A monopoly is a market structure which is typically characterized by a single-seller who sells a unique product in the market by dominance. This ultimately implies that, it is a market structure wherein the seller has no competitor because he is solely responsible for the sale of unique products without close substitutes. Any individual that deals with the sales of unique products in a monopolistic market is generally referred to as a monopolist.
For example, a public power company is an example of a monopoly because they serve as the only source of power utility provider to the general public in a society.
Additionally, a public power company refers to a company that provides power (electricity) utility to the general public of a society.
Hence, a market that has a single supplier of a product with no close substitutes and barriers to entry is a pure monopoly.