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?

• AThere is a considerable degree of variation in shade of color between weeds of different species.  
• BThe shade of color of some plants tends to change appreciably over the course of their growing season.  
• CWhen crops are weeded manually, overall size and leaf shape are taken into account in distinguishing crop plants from weeds.  
• DSelection 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.  
• EFarm 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.