Which of the following most accurately describes the long-run period?

a. The long run is a period of time in which a firm is unable to vary some of its factors of production.

b. In the long run, a firm is able to expand output by utilizing additional workers and raw materials, but not physical capital.

c. The long run is of sufficient length to allow a firm to alter its plant capacity and all other factors of production.

d. The long run is of sufficient length to allow a firm to transform economic losses into economic profits.

e. Both (a) and (b) most accurately describe the long-run period.