Arrange the following steps in the correct order to understand how economic profit influences firm behavior in an oligopoly after a new competitor enters the market: A) Firms adjust their pricing strategies based on competitors' actions; B) A new competitor enters the market and affects supply; C) Firms evaluate their economic profit by comparing price to average total cost; D) The market reaches a new equilibrium price and quantity.

To understand how economic profit influences firm behavior in an oligopoly after a new competitor enters the market, we start with a new competitor entering the market and affecting supply. This is step B. Once this happens, firms in the market will evaluate their economic profit by comparing the price of their products to their average total cost, which is step C. After evaluating their profits, firms will adjust their pricing strategies based on the actions of their competitors, which is step A. Finally, as firms respond to these changes, the market reaches a new equilibrium price and quantity, completing the process with step D.