#18 - Advertisement: Attention pond owners! Ninety-eight

[Administrator]

Complete Question Explanation

Assumption. The correct answer choice is (E)

The conclusion of this stimulus is the central claim of this advertisement, presented in the last sentence. The argumentation of the ad is as follows:

• Premise 1: BTI kills 98% of mosquito larvae.
  
  Premise 2: BTI is non-toxic to other life in the pond.
  
  Conclusion: BTI will allow killing of mosquito larvae without reducing populations of fish, frogs, and beneficial insects.

This appears to be a reasonable argument, so we may consider the Assumption Negation technique to check any contender answer choices. Answer choice (A), negated, would say that killing larvae is not the most effective way to control mosquitoes—this has no effect on the claim in the ad. Answer choice (B) would actually work against the ad’s claim, so it cannot be an assumption on which the ad relies. Answer choice (C), when negated, would say that there are other pests—this does not work against the ad. Answer choice (D) is irrelevant, since the argument definitely does not reference application procedures.

Answer choice (E): This is the correct answer choice. Answer choice (E), when negated, says basically, “some of the other pond life forms do rely on mosquito larvae for food.” If this is the case, then the ad’s claim is defeated, since the author’s assertion is that mosquitoes can be controlled without hurting other life around the pool. Since this answer choice, when negated, does defeat the ad’s conclusion, this must reflect a defender assumption on which the ad relies.

[lathlee]

Hi. I had contenders of answer choices A and E but chose A) as the final answer but the answer sheets says it is E) why?
cuz the negated version of A) would be : The most effective way to control the members of mosquitoes in a given area is Not to destroy the mosquito larvae in that area.

which hurts the conclusion of

So by using BTi regularly to destroy their larvae, you can greatly reduce populations of pesky mosquitoes that hatch in your pond, and you can do so without diminishing the populations of fish, frogs, or beneficial insects in and around the pond.

[Emily Haney-Caron]

Hi lathlee,

I think what tripped you up here is reading too much into the conclusion. Here, the conclusion isn't saying BTI is the best way to reduce larvae; just that it is an effective way. So, for example, a nuclear bomb would likely kill even more larvae; however, that doesn't harm the conclusion at all, even if that's true. The negation of A, therefore, doesn't really impact the conclusion, but the negation of E damages it substantially.

Hope that helps!