A、They grow larger and stronger. B、They exhibit greater stress and anxiety. C、They begin to establish their own territories. D、T

Today’s lecture will concern the territory an animal claims. First, let’s define the term “territory”. (20) A territory for an animal is a geographical area that an animal chooses to dominate over. While here the key word is dominance, animals such as birds and mammals seem to exert control over their territory. And they are more aggressive in defending the centre or core i.e. the central part of their territory and they become less aggressive in the outer limits of their territory. A good example of the animal’s territoriality is the behavior of a pet dog. Have you ever seen a small dog attempting to chase a larger dog out of the backyard? If you have, you probably noticed that (21) once the larger dog has escaped out of the premises, the small dog would give up the chase and calm down immediately. This is exactly what happened to an animal when its territory is disturbed. But does the answer say anything about the human being? (22) Many psychological studies review that animals show great stress if they are put too close to one another. What does this have to do with us? Aren’t people put too close together in cities? And don’t city dwellers exhibit more crime and anxiety than rural dwellers? The theory that the human being has a territory is highly speculative and still needs much more careful research.
Questions 20 to 22 are based on the passage you have just heard.
20. Which of the following is the best definition of the term “territory” for an animal?
21. Why does the small dog give up the chase?
22. According to scientists, what happens if animals are put too close together?