All of the cargo ships of the Blue Star Line are over 100 meters long, and all of its passenger ships are under 100 meters long. Most of the ships of the Blue Star Line were built before 1980. All of the passenger and cargo ships of the Gold Star line were built after 1980, and all are under 100 meters long. The dockside facilities of Port Tropica, which is open only to ships of these two lines, can accommodate only those ships that are less than 100 meters long. The S. S. Coral is a cargo ship that is currently docked at Port Tropica. If the statements above are true, which one of the following must be true on the basis of them? ['All of the ships of the Blue Star Line are older than any of the ships of the Gold Star Line.', 'The S. S. Coral belongs to the Blue Star Line.', 'The S. S. Coral was built after 1980.', 'Port Tropica is served only by cargo ships.']