B.     The narwhals’ distinctive characteristic lies in the presence of a long 2.5-meter spiralling tusk that protrudes from the males’ foreheads, resembling a unicorn. The horn-like formation, however, is a long-left tooth. The right tooth remains embedded in the skull and measures roughly 30 centimetres. Female tusks have a more regularly defined morphology. They are much shorter, straighter, and do not collect as many algae on the surface, thus appearing whiter.

C.     For hundreds of years the purpose of the tusk on the “unicorn whale” has puzzled scientists and local aboriginal elders alike. A northern aboriginal legend explains the narwhals’ tusk was created when a woman shooting with a harpoon rope was dragged into the ocean after the harpoon had struck a large narwhal. She then was transformed into a narwhal herself, and her hair, which was long and twisted, became the characteristic of the spiral tusk. In academic circles, the tusk remains an evolutionary mystery that defies many of the known principles of mammalian teeth. Preliminary studies suggest the tusk enables whales to determine the salinity levels and allows them to detect food in their environment.

D.    Narwhal behaviour also intrigues researchers. Males frequently engage in episodes of rubbing their tusks together, or “tusking,” for as-yet unknown reasons. The same behaviour is not observed in the female counterparts or between males and females. Some studies theorize about the possibility of these being mating behaviours aimed at displaying genetic superiority. Support for such a theory, however, has proved scarce since unlike other mammalian species the behaviour is not aggressive. Narwhals are a migratory species. In an attempt to learn about their migration patterns and social behaviour, their populations are being observed and recorded through satellite tracking conducted by scientists in Canada and Greenland.

E.     Not given in any of the above paragraphs