According to a prediction of the not-so-distant future published in 1940, electricity would revolutionize agriculture. Electrodes would be inserted into the soil, and the current between them would kill bugs and weeds and make crop plants stronger. Which of the following, if true, most strongly indicates that the logic of the prediction above is flawed? ['In order for farmers to avoid electric shock while working in the fields, the current could be turned off at such times without diminishing the intended effects.', 'Because a planting machine would need to avoid coming into contact with the electrodes, new parts for planting machines would need to be designed.', 'It cannot be taken for granted that the use of electricity is always beneficial.', 'Since weeds are plants, electricity would affect weeds in the same way as it would affect crop plants.']