Charging different prices for the same commodity is a feature of a

Analyze the question: The question is about price discrimination, which means charging different prices for the same product to different buyers. This is not tied to differences in cost. It depends on the buyers' location, age, income, or the time of purchase.

Explain the concept: For a firm to practice price discrimination, it needs:

1. Price-making power. The firm must control price rather than just accept it.
2. Market separation. Buyers in the different markets must not be able to resell to one another.
3. Different elasticities of demand in the separate markets.

A monopolist meets these conditions. It is the sole seller, so it is a price maker. Examples are an electricity distributor charging different rates to households and industries, or a transport company charging students less than adults.

Evaluate the options:

• A. Perfect competition: Wrong. There are many sellers of a homogeneous product, and every firm is a price taker. A firm that charged more than the market price would lose all its customers.
• B. Commodity market: Wrong. This describes a place where goods like cocoa or crude oil are traded. It is not a market structure with this feature.
• C. Monopolistic competition: Not the best answer. Firms sell differentiated products, and their price-making power is limited by many close substitutes. Price discrimination is not its defining feature.
• D. Monopoly market: Correct. A single seller with substantial market power can separate buyers and charge different prices for the same good.

Exam tip: Whenever you see "price discrimination" or "different prices for the same product," think monopoly. Remember it as: "Mono = one seller, so the seller sets the price."