Final answer:
A monopolist's supply curve is not vertical; instead, monopolists operate on a downward-sloping demand curve, choosing their output level to maximize profits, which does not result in a fixed supply quantity at different prices.
Step-by-step explanation:
The statement that 'a monopolist's supply curve is vertical' is false. In fact, monopolists do not have a supply curve in the traditional sense. A perfectly competitive firm perceives the demand curve it faces as flat, meaning they can sell any quantity at the market price. However, a monopolist faces the market demand curve, which is downward-sloping. This means that if they want to sell more, they must lower the price, creating a trade-off between price and quantity that doesn't exist for competitive firms. Monopolists choose the price and quantity combination that maximizes their profits rather than responding to a market price with a certain supply quantity like competitive firms do.
Because the monopolist is the sole producer in the market, they face the entire market demand curve, leading them to make strategic decisions about price and quantity to maximize profits. The monopolist's need to balance total revenue and price when deciding on output level results in a total revenue curve that initially increases, then flattens, and eventually decreases, rather than a vertical supply curve.