A perfectly competitive firm's demand curve is

Which one of the following is not an accurate description of the activities in which labor unions engage?

A) Control competition among workers for jobs. B) Encourage consumers to purchase union-made products exclusively. C) Enforce seniority criteria when employers are contemplating layoffs. D) Help workers compete against corporate employers. E) Protect workers against arbitrary treatment by management.

A cubic cost function implies:

A) a U-shaped average variable cost curve. B) a U-shaped marginal cost curve. C) a U-shaped average cost curve. D) all of the above