.      As the world's largest terrestrial carnivore  ,the polar bear is the king of the great white north. Adult males can measure more than 9 feet in length and weigh between 770 and 1,430 pounds. The bear's body and neck are elongated, and the head is narrow and long with small, rounded ears. Polar bear populations can be found in northern Canada, Greenland, Norway and Russia, and there have been reports that polar bear tracks have been found as far north as the North Pole. The 5,000,000-square-mile range of the polar bear circles the Arctic and contains stretches of open water where seals are easily caught. Polar bears live on the annual Arctic sea ice that provides a platform from which they can hunt. They hunt seals on the sea ice by breaking into seal dens in the sea ice. The dens aren't visible from above,but seeing is less important than smelling to a polar bear -- with their keen sense of smell,polar bears can sense the breathing holes of seals in their dens beneath the snow and ice. As the southern edge of the Arctic ice cap melts in summer, polar bears are stranded  on land and spend their summers fasting  ,living off body fat stored from hunting in spring and winter. It might come as a surprise that this species faces an uncertain future. Climate change is causing the disappearance of sea ice from which polar bears hunt seals. Sea ice in the Arctic is melting earlier and forming later each year. With about 22,000 polar bears living in the wild,the species is not endangered at the moment, but its future is far from certain. People have reached an agreement that controls the hunting of polar bears and directs each nation to protect their habitats, but it does not protect the bears against the biggest man-made threat to their survival : global warming. If current warming trends continue, scientists believe that polar bears may disappear within 100 years. Polar bears search for seals mainly through their   _  .
eyes ears noses necks
Question: .      As the world's largest terrestrial carnivore  ,the polar bear is the king of the great white north. Adult males can measure more than 9 feet in length and weigh between 770 and 1,430 pounds. The bear's body and neck are elongated, and the head is narrow and long with small, rounded ears. Polar bear populations can be found in northern Canada, Greenland, Norway and Russia, and there have been reports that polar bear tracks have been found as far north as the North Pole. The 5,000,000-square-mile range of the polar bear circles the Arctic and contains stretches of open water where seals are easily caught. Polar bears live on the annual Arctic sea ice that provides a platform from which they can hunt. They hunt seals on the sea ice by breaking into seal dens in the sea ice. The dens aren't visible from above,but seeing is less important than smelling to a polar bear -- with their keen sense of smell,polar bears can sense the breathing holes of seals in their dens beneath the snow and ice. As the southern edge of the Arctic ice cap melts in summer, polar bears are stranded  on land and spend their summers fasting  ,living off body fat stored from hunting in spring and winter. It might come as a surprise that this species faces an uncertain future. Climate change is causing the disappearance of sea ice from which polar bears hunt seals. Sea ice in the Arctic is melting earlier and forming later each year. With about 22,000 polar bears living in the wild,the species is not endangered at the moment, but its future is far from certain. People have reached an agreement that controls the hunting of polar bears and directs each nation to protect their habitats, but it does not protect the bears against the biggest man-made threat to their survival : global warming. If current warming trends continue, scientists believe that polar bears may disappear within 100 years. Polar bears search for seals mainly through their   _  .
A. eyes
B. ears
C. noses
D. necks
Answer: