Question Type
Weaken
Stimulus
The argument concludes that there is no reason to suppose that laundry detergents that are advertised as ecologically friendly are less damaging to the environment than other laundry detergents. The support for this view is that most of the ingredients in laundry detergents, including the so-called ecologically friendly ones, have unknown environmental effects. However, it's important to note that the argument also mentions surfactants, which is known to have damaging environmental effects. And we learn that all laundry detergents have surfactants.
Anticipate
The big question is whether one laundry detergent can be less harmful to the environment than another even though they both have the same environmentally damaging ingredient. One might suspect that that having less of the environmentally damaging ingredient could influence the amount of environmental damage that is to be expected from the use of one laundry detergent or another.
Correct Answer
(A) weakens the argument by providing a reason why ecologically friendly laundry detergents might do less damage to the environment, namely that they have less of the known environmentally damaging ingredient (i.e., surfactants).
Incorrect Answers
(B) is out of scope. While there is a question about the environmental impact of ingredients other than surfactants, the argument does not assume that those other ingredients either do, or do not, harm the environment.
(C) is not specific enough. This answer choice does not indicate which laundry detergents use the less damaging sort of surfactants. Notice that answer choice (A) provides a reason why ecologically friendly laundry detergents might be safer (lower amount of surfactants) but that the reason in this choice for less environmental damage (different kind of surfactants) is not assigned to any particular kind of laundry detergent.
(D) is out of scope for the same reason answer choice (B) is.
(E) is out of scope. We are not concerned about how effective each brand of laundry detergent is, but rather what the environmental impact would be of using it.
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