Economic rent is the portion of a resource's total earnings above its opportunity cost

The figure above shows a perfectly competitive firm. In the short run, the firm will shut down

A) only if the AVC of producing 10 units is less than $20. B) only if the AVC of producing 10 units is more than $20. C) only if the AVC curve reaches its minimum before 10 units are produced. D) always.

In which market structures is the firm able to earn long-run economic profits?

A) perfect competition and monopolistic competition B) monopolistic competition and oligopoly C) oligopoly and monopoly D) monopolistic competition, oligopoly and monopoly