Final answer:
Marginal revenue product equals marginal product times the price of the product for firms in a perfectly competitive market because they are price-takers. In other market structures with some market power, marginal revenue differs as firms face a downward-sloping demand curve. Therefore, the correct option is B.
Step-by-step explanation:
When considering a firm's revenue, the concept of marginal revenue product (MRP) is crucial, particularly in understanding how it relates to the firm's market structure. For a firm operating in a perfectly competitive market, the marginal revenue product is calculated by multiplying the marginal product (MP) by the price of the product. Essentially, this happens because a perfectly competitive firm is a price-taker, meaning it can sell as much as it wants at the prevailing market price without affecting the price itself. Hence, its marginal revenue equals the price (MR = P), leading to the marginal revenue product being the product of MP and the firm's output price.
In contrast, firms with some market power, like those in oligopolistic or monopolistic markets, face a downward-sloping demand curve. Such firms must lower their prices to sell additional output, making the marginal revenue product equal the marginal product of labor multiplied by the marginal revenue, which is not the same as the price.