Final answer:
The Marginal Revenue line for a monopoly is twice as steep as the Demand line, reflecting the conditional nature of a monopolist's market power and the impact of price reductions on revenue when selling more units (A).
Step-by-step explanation:
The Marginal Revenue line for a monopoly is 2x as steep as the Demand line. The marginal revenue curve for a monopolist is determined by the market demand curve, which is downward sloping due to the conditional nature of a monopolist's market power. This causes the marginal revenue curve to always lie beneath the demand curve.
When a monopolist increases their quantity sold, they must decrease their price to do so, affecting their marginal revenue. Unlike total revenue, which may first increase as output rises and then decrease as the monopolist reduces the price to sell more, marginal revenue decreases steadily. This key difference is essential to understanding a monopolist's pricing and output decisions, aiming to maximize profit rather than revenue.