In the market structure called monopoly in microeconomics, a monopoly exists where there is exactly how many sellers in a particular market?

Introduction / Context:
Market structures such as perfect competition, monopoly, monopolistic competition, and oligopoly are core ideas in microeconomics. A monopoly represents one extreme of this spectrum. Examinations often ask simple but important questions like how many sellers characterise a monopoly. Understanding that a monopoly is defined by the presence of a single seller is essential for correctly analysing pricing and output decisions under this market structure.

Given Data / Assumptions:
- The question refers to the market structure called monopoly. - We are asked about the number of sellers in such a market. - The options list different numbers of sellers: 1, 2, 5, and 10. - We assume the standard textbook definition of monopoly in microeconomics.

Concept / Approach:
A monopoly exists when a single firm is the sole producer and seller of a product or service that has no close substitutes within a particular market. This one firm effectively becomes the industry itself. As a result, it has significant control over price and output, unlike firms in competitive markets. The conceptual approach is therefore straightforward: identify the option that states there is exactly one seller controlling the entire market supply.

Step-by-Step Solution:
Step 1: Recall the basic definition: monopoly is a market with a single seller and many buyers, and the product has no close substitutes. Step 2: Consider option a, which explicitly says 1 seller controlling the entire market supply. This exactly matches the definition. Step 3: Option b, with 2 sellers, would more closely resemble a duopoly, not a monopoly. Step 4: Option c, with 5 sellers, suggests an oligopolistic structure where a few firms dominate, but it is not a single-seller market. Step 5: Option d, with 10 sellers, suggests more competition and is even further from the idea of monopoly. Step 6: Therefore, the only option that correctly describes a monopoly is option a with 1 seller.

Verification / Alternative check:
Microeconomics textbooks and competitive exam guides uniformly define monopoly as a market situation with a single seller and many buyers. Real-world examples often include local utility providers in areas where no other firm supplies the same service. This consistent emphasis on one seller confirms that the correct answer must mention exactly one seller, not any larger number.

Why Other Options Are Wrong:
Option b describes a duopoly, a market dominated by exactly two firms, which is conceptually different from monopoly. Option c, with 5 sellers, suggests a small group of firms typical of oligopoly, where a few firms exert considerable influence but none is the sole seller. Option d, with 10 sellers, implies even more competition and is inconsistent with a monopoly. Since monopoly requires a single seller, any option with more than one seller is incorrect.

Common Pitfalls:
Some students confuse monopoly with dominant firm situations, where one firm has a very large share but is not literally the only seller. Examinations, however, use the strict textbook definition for theoretical questions. Another pitfall is to overthink the question and imagine that numerical values are approximate. In theory, monopoly is defined as one seller, so you should confidently choose the option that states exactly one seller without trying to reinterpret the concept.

Final Answer:
In a monopoly, there is exactly 1 seller controlling the entire market supply.