Fei Fei #89

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

The argument above makes which
one of the following assumptions?

A.     
Biotechnology
should be directed toward producing plants that do not require artificial
fertilize.

B.      
Fixed
nitrogen is currently the only soil nutrient that must be supplied by
artificial fertilizer for growing wheat crops.

C.      
There
are no naturally occurring strains of wheat or other grasses that have
Rhizobium bacteria living in their roots.

D.     
Legumes
are currently the only corps that produce their own supply of fixed nitrogen.

E.      
Rhizobium
bacteria living in the roots of wheat would produce fixed nitrogen.

参考答案：E