EVERYDAY SCIENCE

Detailed explanation-1: -Mammals are the only animals that have hair. It grows from the outer layer of the skin. A dense covering of hair is often called fur or wool and insulates. Glands in the skin release oils which help to keep the fur waterproof and protects against rain and cold.

Detailed explanation-2: -Hair is present in differing degrees on all mammals. On adult whales, elephants, sirenians, and rhinoceroses body hair is limited to scattered bristles. In most other mammals the hair is abundant enough to form a thick coat, while humans are among the most hairless of all mammals.

Detailed explanation-3: -Mammals have hair or fur, birds have feathers, reptiles have dry scales, amphibians have soft, moist skin, and fish have wet, slimy scales.

Detailed explanation-4: -In modern mammals, hair serves to insulate, to conceal, to signal, to protect, and to sense the immediate surroundings. Insulation serves to conserve heat, but also, as in the case of diurnal desert animals such as the camel, to protect against excessive heat.

Detailed explanation-5: -Cetaceans, like whales, dolphins and porpoises are the largest group of hairless mammals. they don not need body hairs as they possess blubber for insulation. Hence, option A is correct.