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?（结论的具体性）

1. There is a considerable degree of variation in shade of color between weeds of different species.
2. The shade of color of some plants tends to change appreciably over the course of their growing season.
3. When crops are weeded manually, overall size and leaf shape are taken into account in distinguishing crop plants from weeds.
4. 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.
5. 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.

E是无关。 farmers在不需要拔草的时候干其他的农活，不能support the plan。
A是无关，要注意是crops和weeds的颜色不同，而各种weeds的颜色有多么不同是无关的。
D，正因为可以把crops改成需要的颜色，所以这个技术才有用。

哦，对！A是在weeds里比较，要区别的是crops和weeds，
发现还是阅读水平的问题.

谢谢！