我国的各种地形中，分布面积最广的是（　　）

A．高原

B．平原

C．盆地

D．山地

Researchers have discovered a new poison, bromethalin, that is lethal to all rats, even to those species that have become immune to other poisons, as well as to those rats that eat only the most minute quantities. Tests have demonstrated that rats will not learn to avoid bromethalin and that carcasses of rats killed by bromethalin pose no threat to the well-being of other animals.
Which of the following statements, if true, would support the researchers’ claim that carcasses of rats killed by bromethalin will not pose a threat to other animals

A．Rats that consume bromethalin die immediately.

B．Animals, prompted by curiosity, often examine carcasses that appear in their territory.

C．Chemicals in the digestive tract of dead rats quickly break bromethalin down into a nontoxic substance.

D．Traces of bromethalin remain in the rat’s mouth and saliva after the rat eats the poison.

E．(E) Certain animals are scavengers and feed habitually on refuse and dead flesh.