Question

One could argue correctly that:

a. all firms in any industry can earn short-run but not necessarily long-run positive economic profit.
b. all firms in any industry can earn long-run but not necessarily short-run positive economic profit.
c. all firms in any industry can earn both short-run and long-run positive economic profit.
d. no firm in any industry can earn a long-run positive economic profit because all price changes made by any firm will be followed by all of the other firms.
e. all firms in any industry can earn a short-run positive profit if economies of scale exist.

Answer 1

a. all firms in any industry can earn short-run but not necessarily long-run positive economic profit.

Step-by-step explanation:

A firm economic profit if its accounting profit is greater than opportunity cost.

A firm earns accounting profit if its total revenue is greater than its total explicit cost.

A monopoly and oligopoly can earn positive economic profit in the short and long run because the industries have high barriers to entry and exit of firms.

On the other hand, a perfect competitive industry can earn only economic profit in the short run. Because of low barriers to entry of firms, if a firm is earning economic profit, in the long run new firms would enter into the industry and drive economic profit to zero.

I hope my answer helps you