接收的频率随声源运动而发生改变的现象称为（）

A.自然反射

B.混响

C.多普勒效应

D.传播

E.入射角度

Proponents of organic farming claim that using chemical fertilizers and pesticides in farming is harmful to local wildlife. To produce the same amount of food, however, more land must be under cultivation when organic farming techniques are used than when chemicals are used. Therefore, organic farming leaves less land available as habitat for local wildlife.
Which one of the following is an assumption on which the author’s argument depends

A．Chemical fertilizers and pesticides pose no health threat to wildlife.

B．Wildlife living near farms where chemicals are used will not ingest any food or water containing those chemicals.

C．The only disadvantage to using chemicals in farming is their potential effect on wildlife.

D．The same crops are grown on organic farms as on farms where chemicals are used.

E．(E) Land cultivated by organic farming methods no longer constitutes a habitat for wildlife.