Chemist: The molecules of a certain weed-killer are always present in two forms, one the mirror image of the other. One form of the molecule kills weeds, while the other has no effect on them. As a result, the effectiveness of the weed-killer in a given situation is heavily influenced by which of the two forms is more concentrated in the soil, which in turn varies widely because local soil conditions will usually favor the breakdown of one form or the other. Thus, much of the data on the effects of this weed-killer are probably misleading. Which one of the following, if true, most strengthens the chemist's argument? ["Almost all of the data on the effects of the weed-killer are drawn from laboratory studies in which both forms of the weed-killer's molecules are equally concentrated in the soil and equally likely to break down in that soil.", 'In general, if the molecules of a weed-killer are always present in two forms, then it is likely that weeds are killed by one of those two forms but unaffected by the other.', "Data on the weed-killer's effects that rely solely on the examination of the effects of only one of the two forms of the weed-killer's molecules will almost certainly be misleading.", "Of the two forms of the weed-killer's molecules, the one that kills weeds is found in most local soil conditions to be the more concentrated form."]