According to the text, mark the CORRECT item: 

                                       The intrigue behind the Bermuda Triangle

       On a sunny day nearly 80 years ago, five Navy planes took off from their base in Florida on a _________ training mission, known as Flight 19. Neither the planes nor the crew were ever seen again. Thus was a legend born. The Bermuda Triangle is an area roughly bounded by Miami, Bermuda, and Puerto Rico. No one keeps statistics, but in the last century, numerous ships and planes have simply vanished without a trace within the imaginary triangle.

       The disappearances have been attributed to the machinations of enormous sea monsters, giant squid, or extra-terrestrials. Alien abductions, the existence of a mysterious third dimension created by unknown beings, and ocean flatulence—the ocean suddenly spewing great quantities of trapped methane—have all been suggested as culprits.

       The reality, say many, is far more prosaic. They argue that a sometimes treacherous Mother Nature, human error, shoddy __________________ or design, and just plain bad luck can explain the many disappearances.

       "The region is highly traveled and has been a busy crossroads since the early days of European exploration," said John Reilly, a historian with the U.S. Naval Historical Foundation. "To say quite a few ships and airplanes have gone down there is like saying there are an ________ lot of car accidents on the New Jersey Turnpike—surprise, surprise."

(Fonte: National Geographic. — adaptado.)