Because of a Patent, XYZ Plc Is the Only Manufacturer

Because of a patent, XYZ plc is the only manufacturer of milk cartons with a special pourer. XYZ plc can earn supernormal profit on the sale of milk cartons with these pourers:

A) in the long run but not the short run because the monopolist will face competition in the short run
B) in the short run but not in the long run because new firms will enter the industry in the long run
C) in the long run because entry into the industry by new firms is blocked
D) only in the long run because government regulations prevent monopolists from earning supernormal profits in the short run