求助~狒狒第89题

89. Rhizobium bacteria living in the rootsof bean plants or other legumes produce fixed nitrogen, which is one of theessential plant nutrients and which for non-legume crops, such as wheat,normally must be supplied by applications of nitrogen-based fertilizer. So ifbiotechnology succeeds in producing wheat strains whose roots will play host toRhizobium bacteria, the need for artificial fertilizers will be reduced.

The argument above makes which one of thefollowing assumptions?

(A) Biotechnology should be directed towardproducing plants that do not require artificial fertilize.

(B) Fixed nitrogen is currently the onlysoil nutrient that must be supplied by artificial fertilizer for growing wheatcrops.

(C) There are no naturally occurringstrains of wheat or other grasses that have Rhizobium bacteria living in theirroots.

(D) Legumes are currently the only corpsthat produce their own supply of fixed nitrogen.

(E) Rhizobium bacteria living in the rootsof wheat would produce fixed nitrogen.

答案给的是E，但是根据Rhizobium bacteria 在根部能产生固氮->人工肥料可以减少使用这个逻辑，为什么B不是assumption之一呢。

如果出了固氮外人工化肥还提供别的营养，那即使固氮可以通过自己生成，人工化肥还是不能少啊

请大牛指教