To maximize profit, a perfectly competitive firm:. a) should sell the quantity of output that results in a value for total revenue that is equal to total cost.
b) Should produce the quantity of output that results in the greatest difference between marginal revenue and marginal cost.
c) should produce the quantity of output that results in the greatest difference between total revenue and total cost.
d) shouls sell thw quantity of output determined by the interaction between the indusrey demand and supply.

D

Explanation:

A perfect competition is characterized by many buyers and sellers of homogenous goods and services. Market prices are set by the forces of demand and supply. There are no barriers to entry or exit of firms into the industry.  

In the long run, firms earn zero economic profit.  If in the short run firms are earning economic profit, in the long run firms would enter into the industry. This would drive economic profit to zero.  

Also, if in the short run, firms are earning economic loss, in the long run, firms would exit the industry until economic profit falls to zero.  

Profit is maximised where marginal cost equals marginal revenue.

answer a is correct answer