阅读理解：阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项．

Space around Animals

　　Every living thing has a physical boundary that separates it from its external (外面的) environment. Beginning with the bacteria and the simple cell and ending with man every organism(组织) has a certain limit which marks where it begins and ends.

　　Anyone who has had experience with dogs particularly in the countryside such as on farms is familiar with the way in which the dog handles space. In the first place the dog knows the limits of his master's yard and will defend it against encroachment. There are also certain places where he sleeps: a spot next to the fireplace a spot in the kitchen or one in the dining room if he is allowed there. In short a dog has fixed points to which he returns time after time depending upon the occasion. One can also observe that the dog creates zone he is in and a trespasser (非法侵入者 )can cause different behavior when he crosses the invisible lines which are meaningful to the dog.

　　This is particularly noticeable in females with puppies. A mother who has a new litter (一胎所生的小动物) in a little used barn will claim the barn as her territory. When the door opens she may make a slight movement or stir in one corner. Nothing else may happen as the intruder moves ten or fifteen feet into the barn. Then the dog may raise her head or get up circle about and lie down as another visible boundary is crossed. One can tell about where the line is by withdrawing and watching when her head goes down. As additional lines are crossed there will be other signals a thumping (重击) of the tail a low moan or a growl.

1．A dog on a farm knows________.

[　　]

A．the size of its master's yard

B．the only fixed place where he should sleep

C．he should not sleep in the kitchen

D．the area that it should defend

2．A female dog with puppies will probably ________.

[　　]

A．attack any stranger who comes near

B．signal differently according to different occasions

C．raise her head at the sight of a stranger

D．growl when a stranger leaves her territory

3．It can be inferred from the third paragraph that mother dogs ________.

[　　]

A．have a sense of gradual territory

B．protect their babies cautiously

C．are ready to attack strangers

D．prefer to raise babies in barns

4．Which of the following is FALSE according to the passage?

[　　]

A．Dogs sleep at certain places in the yard or house.

B．Dogs will respond to territory trespass.

C．The boundary lines are visible and meaningful to dogs.

D．Not all living things have a physical boundary.