LSAT Explanation PT 26, S3, Q14: A commercial insect trap consists of

LSAT Question Stem

Which one of the following, if true, most seriously undermines the hypothesis? 

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

The argument in the passage states that commercial insect traps containing pesticide mixed with glucose have become less effective in households where they have been used regularly for the past several years. Research scientists hypothesize that this decrease in effectiveness is due to successive generations of pests developing resistance to the pesticide. The structure of the argument is as follows:

Premise: Insect traps containing pesticide and glucose have become less effective in households where they have been used regularly for several years.

Conclusion: Successive generations of pests have developed resistance to the pesticide, causing the traps to be less effective.

The question type is a Weaken question, which asks us to find an answer choice that most seriously undermines the hypothesis presented in the passage.

An "Evaluate" question for this argument could be: "Is there any other reason for the decrease in trap effectiveness besides the pests developing resistance to the pesticide?"

Now, let's analyze the answer choices:

a) In households where the traps have been used regularly, the proportion of insect pests that have a natural aversion to eating glucose has increased with each successive generation.

This answer choice provides an alternative explanation for the decrease in trap effectiveness, suggesting that the pests are avoiding the glucose rather than developing resistance to the pesticide. This directly undermines the hypothesis and is the correct answer.

b) Even when only a few individuals out of an entire generation of insects survive the effects of a pesticide, the offspring of those individuals are usually resistant to that pesticide.

This answer choice does not weaken the hypothesis; instead, it supports the idea that resistance to the pesticide can be passed down through generations. This choice does not provide an alternative explanation for the decrease in trap effectiveness.

c) After eating glucose mixed with the pesticide, insects that live in households that do not use the trap tend to die in greater numbers than do insects from households where the traps have been used regularly.

This answer choice does not provide a clear causal connection between the drop in deaths and any other cause. It doesn't provide an alternative explanation for the decrease in trap effectiveness, and it is not clear what it proves. Thus, it does not undermine the hypothesis.

d) After the manufacturer of the traps increased the concentration of the pesticide used in the traps, the traps were no more effective in eliminating household insect pests than were the original traps.

This answer choice does not provide an alternative explanation for the decrease in trap effectiveness. It simply states that increasing the pesticide concentration did not improve the traps' effectiveness, but it doesn't provide a reason for the original decrease in effectiveness.

e) The kind of glucose used to bait the traps is one of several different kinds of glucose that occur naturally.

This answer choice does not provide an alternative explanation for the decrease in trap effectiveness. It simply provides information about the glucose used in the traps but does not undermine the hypothesis that pests developed resistance to the pesticide.

In conclusion, the correct answer is A, as it provides an alternative explanation for the decrease in trap effectiveness, undermining the hypothesis that successive generations of pests developed resistance to the pesticide.