Which of the following is true about the long runaverage cost curve?

• The long run average cost curve is comprised of all the lowestpoints of each of the short run average cost curves because no firmwill operate at a level of higher per-unit costs in the long runthan in the short run.

• The long run average cost curve can be found as the MC fromabove the shut down point onward.

• The long run average cost curve is shaped like a bell and risesbecause of economies of scale while falling because ofdiseconomies.

• The long run average cost curve cannot be equal to or lie belowany short run average cost curve because in the short run allfactors of production can be variable.