【正确答案】The lecture outlines two uses of animal danger calls by the monkeys in Africa, where leopards pose a serious danger. In the first case, a monkey sends an alarm call when a leopard appears. Other monkeys that hear the call flee immediately without seeing if the leopard is present.
In the second case, a monkey may give the alarm when there is no leopard at all. He does this in order to get access to some valued food source and eat everything alone since the others flee after hearing the alarm and do not check to see if there is actually danger.

【答案解析】[听力原文]
W: Sometimes, I know, biology can be a little boring. The same animals show small variations of the same behavior. So today I have a treat for you. I'm going to tell you a different story. You've all heard about "The Boy Who Cried Wolf." Well this is the tale of "The Monkey Who Cried Leopard."
Usually, of course, animal cries of alarm are just that: they warn other group members of some danger. Take monkeys. In Africa, the big danger to monkeys is leopards. Leopards like to hide in trees and can thus attack monkeys at home, as it were. Usually if a monkey spots a leopard, he makes a rasping, scratching noise that has all the other monkeys fleeing away through the trees.
But this doesn't always happen. Sometimes when there is no leopard around, a monkey will give the alarm and the other monkeys run away. Why does he do this? Well, I just said there is no leopard or any other danger. But there is food. In a word, the guard monkey is greedy. He sends his hairy comrades off scampering away, and he can enjoy the whole food supply by himself. The trick usually works because animals usually cannot afford to pause and check whether there is actually any danger.

Alternative Wording(替换表达)
Synonyms (a)danger call—distress call (b) pose—represent
(c)flee—run away (d)give the alarm—sound the alarm
Paraphrases He does this so he can have sole opportunity to coveted food sources, since the others run away before they determine whether there is danger.