题目内容：

(2014·德州模拟)Some animals will defend their territory by fighting with those who try to invade it.Fighting，however，is not often the best choice，since it uses up a large amount of energy，and can result in injury or even death.Most animals rely on various threats，either through sounds or smells.The songs of birds，the drumming of woodpeckers and the loud calls of monkeys are all warnings that carry for long distances，advertising to possible invaders that someone else’s territory is being approached.Many animals rely on smells to mark their territories or leaving droppings around the territories.Other animals will be warned off the territory without ever meeting with the territory’s defender.

Sometimes，these warnings may be ignored，and an invader may move accidentally into a neighboring territory，or two animals may meet near the border of their nearby territories.When the two animals meet，they will generally threaten each other with visual (视觉的) displays.These displays will often exaggerate an animal’s size by putting up feathers or fur，or will show off the animal’s weapons.The animals may go through all the behavior of fighting without ever actually touching each other.The displays are generally performed best near the center of an animal’s territory，where it is more likely to attack an invader and where retreating becomes more of a choice.

Actual fighting usually only happens in overcrowded conditions，when resources are not enough.Serious injury can result，and old or sick animals may die，leading to a more balanced population size.Under most natural conditions，territoriality is an effective way of maintaining a healthy population.The study of social behaviors such as territoriality in animals may also help us to understand human society.

1.What topic is the passage mainly involved in?

A．What animals’ territory is usually like.

B．How animals deal with different threats.

C．How animals defend their territory.

D．Where animal fights take place frequently.

2.For most animals，what’s their first response to the possible invaders to defend their    territory?

A．Fighting in groups.

B．Threatening and warning.

C．Escaping before being hurt.

D．Asking partners for help.

3.What does the underlined word “exaggerate” in the second paragraph mean?

A．enlarge   　B．change 

C．shake  　D．shrink

4.An actual fight will happen when________.

A．animals meet near the border of their territories

B．the invader enters the defender’s territories

C．the defender notices the invader smaller than itself

D．the living resources are limited in the territory

5.The last paragraph tells us that territoriality has an influence on the________of the animals.

A．communication 　B．condition

C．population  　D．migration