Final answer:
In a perfectly competitive market like the one LMNOP, Inc. is in, every time the firm sells a cell phone charging cable, its total revenue increases by the fixed market price of the cable.
Step-by-step explanation:
Every time LMNOP, Inc., a firm in a perfectly competitive market, sells a cell phone charging cable, its total revenue increases by a fixed amount equal to the market price. In a perfectly competitive market, a firm's marginal revenue is the same as the market price because the firm's demand curve is perfectly elastic; this means the firm can sell an additional unit of their product for the same price as the previous units. Consequently, for LMNOP, Inc., the increase in total revenue from selling an additional charging cable reflects the constant market price of that cable.
In a perfect competition scenario, when determining highest profit, a firm compares total revenue and total cost. Profits are maximized when the quantity produced is such that marginal revenue equals marginal cost, and the market price is above the average cost of production.