CR36441.01 – Consumer advocate
Question Consumer advocate: In our nation, food packages must list the number of calories per food serving. But most of the serving sizes used are
Question
Which of the following most logically completes the argument below?
When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights, because the lights attract flying insects. In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects. This change is likely to result in a drop in the population of insect-eating bats in Greenville, since __________.
(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)
Solution
Understanding the Passage
When mercury-vapor streetlights are used in areas inhabited by insect-eating bats, the bats feed almost exclusively around the lights,
This statement talks about areas inhabited by insect-eating bats. When mercury-vapor streetlights are used in such areas, the bats feed almost exclusively around the lights.
because the lights attract flying insects.
This part gives an explanation for why bats feed almost exclusively around the light. Because the lights attract flying insects. (This perhaps makes it easier for bats to prey on insects)
In Greenville, the mercury-vapor streetlights are about to be replaced with energy-saving sodium streetlights, which do not attract insects.
In Greenville, the above type of streetlights are about to be replaced with streetlights that do not attract insects. (In such a case, the insect-eating bats will have to look for their food elsewhere.)
This change is likely to result in a drop in the population of insect-eating bats in Greenville, since __________.
The change of streetlights from those that attract insects to those that don’t attract insects is likely to result in a drop of insect-eating bat population.
The statement ends with “since”. Thus, we’re looking for an option that gives us a reason for why the change will lead to a drop in the insect-eating bat population.
Some Thoughts
Would the following option be correct?
The government of Greenville is taking several measures to reduce the population of insect-eating bats.
The answer is that this option is not correct.
Why?
Because while this option gives us a reason to expect a decline in the population of insect-eating bats, it doesn’t give us a reason to believe that the change in streetlights will lead to a decline in the population of the bats.
In other words, we’re looking for a reason for how X will lead to Y. Knowing the presence of other things that can lead to Y will not impact our argument.
For example, if I say, “If Raj studies daily, Raj will increase his chances to succeed on the GMAT”, this statement cannot be impacted by saying “Raj will take the help of a good GMAT tutor”. While taking the help of a good GMAT tutor is expected to increase Raj’s GMAT score, this does not impact whether studying daily will increase his GMAT score.
Evaluating the options
(A) Incorrect .
This option has NO IMPACT on the last statement (the change in streetlights -> drop in the bat population).
This option says that bats do not hunt before sundown.
Let me create a more direct variation of this option:
A1: The bats hunt only when streetlights are on.
Does A1 have an impact on the last statement?
No. Whether the bats only when streetlights are on or whether they hunt even when streetlights are off has no impact on the last statement (given that the passage says that the bats feed almost exclusively around the lights). The change in streetlights is still expected to decrease the population of bats.
(B) Incorrect.
This option has NO IMPACT on the last statement (the change in streetlights -> drop in the bat population).
This option indicates that the bats don’t eat non-flying insects, i.e., they feed exclusively on flying insects.
This option would have explained the last statement (and thus would have been the answer) if the passage had indicated that the change in streetlights is expected to reduce the population of flying insects. However, the change in streetlights is not expected to reduce the population of the flying insects.
Thus, this option doesn’t explain why the change in streetlights will reduce the bat population.
(C) Incorrect.
This option has NO IMPACT on the last statement (the change in streetlights -> drop in the bat population).
Whether the replacement takes a small amount of time or a long amount of time and whether there is a disruption in lighting at certain locations or not HAVE ZERO RELEVANCE to the last statement.
(D) Correct.
This option explains how the change in streetlights will lead to a drop in the bat population.
The option indicates that in the absence of mercury-vapor streetlights, the bats will require much larger quantities of insects to survive.
If so, we have a reason to believe that some bats will not find enough food, given that the insect population is not expected to increase.
In such a case, we have a reason to believe that the bat population will decline as a result of the change in streetlights.
(E) Incorrect.
This option has NO IMPACT on the last statement (the change in streetlights -> drop in the bat population).
This option would have argued against the drop in the bat population if we were removing mercury-vapor streetlights and not putting any streetlights in place of them.
If bats gain no advantage from the visibility of the insects, we get an indication that removing the streetlights will not hamper their success in hunting insects. Thus, we have a reason not to expect a drop in the bat population.
However, this reasoning does not apply to our given context since we’re just changing the type of the streetlights; we’re not removing the streetlights completely. The visibility is not changing in the given situation. Thus, the option is irrelevant to the given situation.
Chiranjeev Singh
An Alumnus of IIM Ahmedabad and with scores of 735 (2024) and 780 (2017) on the GMAT and 99.98%ile on CAT, Chiranjeev is one of the most qualified GMAT tutors in India. Chiranjeev has earlier served as Director of Curriculum at e-GMAT. Chiranjeev has been helping students ace GMAT since 2012. He follows a concept-based methodology to teaching GMAT and is very committed to student success. You may contact him for any private GMAT tutoring needs at CJ@GMATwithCJ.com. He conducts online sessions for students across the world.
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