Suppose it takes a particular company one year to change all of its inputs, including its plant capacity. If, over a two-year period, the firm makes no changes to its plant capacity.
a. it is operating in the long run as long as it changed its level of output.
b. it is still operating in the long run because the period of time is long enough for the firm to make those changes.
c. the firm is operating in the short run, but not the long run.
d. it is operating in the long run as long as it changed at least one input.