单选题
On 5th December, 1945; five bombers from a United States Naval Air Station left Fort Lauderdale, Florida, on a routine training flight over the Atlantic Ocean, east of Florida. A short time later the base received radio messages from the bombers (Flight 19) ,saying that they were lost. Then radio contact was broken The flight did not return, and the planes that were sent to look for the bombers also failed to return. A massive search operation was mounted, but no trace of the missing planes or their pilots was found. They had simply and inexplicably disappeared. This event was sufficient to confirm in many people's minds that the so-called "Devil's Triangle". or "Bermuda Triangle" —a section of the North Atlantic bounded roughly by Bermuda, Florida and Puerto Rico— really was haunted. and in some mysterious way was responsible for the loss of ships and planes. In all, in this area (3 900 000 square kilometres) of open sea, more than 50 ships and 90 planes have mysteriously disappeared. These include the US Navy ship Cyclops in 1918 and the merchant vessel Marine Sulphur Queen in 1963. In the same year two US Air Force KC 135 planes also disappeared without trace. In other words, it is not only small boats and planes that have vanished in the are4,but the most modem and best-equipped too. Perhaps the most dramatic shipping loss in the area was the US Navy nuclear submarine Scorpion. This vessel, like others before her, disappeared without explanation in May, 1968. Some months later she was found on the bottom of the ocean, but the reason for her loss has not been properly explained. Many theories about the area have been proposed, and whole books have been written on the subject. It has been suggested, for example, that the disappearances are caused by unknown magnetic forces from outer space or from the bottom of the sea. There is also a theory about underwater volcanic action that affects shipping, and another that suggests the lost continent of Atlantis, which according to legend lies somewhere beneath the Atlantic, is involve& However, others state that it is more likely that there is nothing special about this imaginary triangle of water, and that it is a product of sensational journalism. After all, ships, boats and planes are lost at sea in all parts of the world due to weather, mechanical failure or human error, and several of the losses are mysterious. The Marie Celeste, an American cargo boat, for example, was found in 1872 off the coast of Portugal in perfect order but with no crew on board. Their disappearance has never been explained. Did some of them mutiny and then escape? Were all the crew killed by some unknown agent? Did they try to escape from some danger or other? We shall probably never know. However, regardless of the theories which exist about the "Bermuda Triangle", ships, boats and planes continue to travel daily trough the area with great frequency and it has not been proven that a higher percentage of accidents and losses occur in this section of the North Atlantic than in other areas of the world's oceans.
单选题
To many people the Bermuda Triangle is really a mystery because ______.