听力原文： Some desert animals can survive the very strong summer heat and dryness because they have very unusual characteristics. The camel, for example, can bear an increase in the temperature of its body and its blood of 9℃. In addition, it can drink an enormous amount of water at one time, then store sufficient water in its red blood cells and other parts of its body to supply its needs for two weeks or more. However, most animals need to maintain a fairly constant body temperature, and will die if it rises more than 5℃. Therefore, they need to find some ways to avoid the strong sun rays. Nor can many animal either store or produce water in their bodies as the camel can. So they must find ways to reduce water loss from their bodies to the lowest degree.
Because very few desert animals can survive the high rays and the temperature, most of them are active during the night. Only after the sun has set does the desert come fully of life. The night is relatively cool, and the darkness provides protection, not only from the sun but also from other animals and from the birds. So the coming of darkness is the signal for the large majority of animals and insects to continue their search of water and food, when morning comes, most of them seek shelter again; many go underground; nearly all find somewhere shady and they can avoid the sun rays there.
What is the best title of the passage？

A. Desert Animal.
B. Camel, An Unusual Animal.
C. A Typical Summer Day and Night of Desert.
D. The Importance of Water on Desert.