Final answer:
The scenario where a single seller is the only one providing a particular product is known as a pure monopoly, which is option 2 on the list provided. The correct option is B.
Step-by-step explanation:
When the seller is the only one selling a particular product, the market structure is known as a pure monopoly. This is notably different from pure competition (or perfect competition), where many firms sell identical products and none have enough market power to influence the price. In a monopolistic competition, many firms sell similar, but not identical, products. An oligopolistic competition, on the other hand, is characterized by a few firms selling identical or similar products.
A classic example of a monopoly is when Microsoft dominated the operating systems market, selling a product with no close substitutes. Monopolies can lead to a lack of competition, potentially resulting in higher prices and less innovation. The correct answer to the student's question is option 2) Pure monopoly, which is when a single firm is the sole provider of a product with no close substitutes.