If a purely competitive firm is producing at the P = MC output and realizing an economic profit,at that output:

A) marginal revenue is less than price.
B) marginal revenue exceeds ATC.
C) ATC is being minimized.
D) total revenue equals total cost.

In a purely competitive market, if a firm is producing where P = MC and realizing an economic profit, it means that the price (which equals marginal revenue in perfect competition) is greater than the average total cost (ATC) at that output level. This is because economic profit occurs when total revenue exceeds total costs, and since price equals marginal revenue in perfect competition, for economic profit to occur, this price/marginal revenue must exceed ATC.