迫切求教！GWD

GWD1-Q33:

A company plans to develop a prototype weeding machine that uses cutting blades with optical sensors and microprocessors that distinguish weeds from crop plants by differences in shade of color.  The inventor of the machine claims that it will reduce labor costs by virtually eliminating the need for manual weeding.

Which of the following is a consideration in favor of the company’s implementing its plan to develop the prototype?

A.      There is a considerable degree of variation in shade of color between weeds of different species.

B.       The shade of color of some plants tends to change appreciably over the course of their growing season.

C.      When crops are weeded manually, overall size and leaf shape are taken into account in distinguishing crop plants from weeds.

D.      Selection and genetic manipulation allow plants of virtually any species to be economically bred to have a distinctive shade of color without altering their other characteristics.

E.       Farm laborers who are responsible for the manual weeding of crops carry out other agricultural duties at times in the growing season when extensive weeding is not necessary.

答案是D，可是我真的怎么想也没有想明白，关selection和genetic manipulation什么事？

麻烦各位NN指点迷津。

题目说根据crop的颜色来区分crop

D是说每种crop的颜色都是独一无二的，所以根据颜色区分crop是可行的

另外，你发错版了。

谢谢ls

为了迅速求解，我两版都发了，嘿

可是还有点疑问

原文说machine可以减少labor costs，也就是eliminating the need for manual weeding

E选项的意思就是说那些farm laborers很清闲，可以被取替。不也是支持了原文吗？