【正确答案】
B
【答案解析】woman: Hi, Jack! Recently I'm planning to write a report on animals' sleep, but after all I still haven’t got a clue. Could you help me?
MAN: Sure! As you know, sleep is a way to relax and save energy for humans and animals. Take humans for example, a good night's sleep will make us feel more active and alert on the following day. But lacking of sleep will be associated with increased blood pressure and cholesterol levels.
woman： Yeah. Indeed, sleep plays an important role in humans' lives. What about other animals?
MAN： Animals need sleep to stay alert while they are awake. If they do not sleep enough, they are most likely to be attacked.
woman: That's to say, the lack of sleep is more horrible than food deficiency. And I guess different animals must have different sleeping time.
MAN: Absolutely! According to one research, smaller animals need more sleep than larger animals. Bats, for example, sleep for more than 20 hours per day, while elephants sleep for about 5 hours or less.
woman： It's interesting! In a word, a regular sleep is the premise of surviving. How significant sleep is!
MAN： Of course! In addition, waking up from sleep is not only a kind of protecting mechanism but also necessary for health and existence.