nikhilsrl wrote:Planners in City X noticed that many of the trees in the city were dying because of exposure to increased levels of air and water pollution. A study they commissioned revealed that sycamore trees actually thrive in environments with elevated levels of carbon monoxide, the main pollutant emitted by automobiles. In order to reverse the trend of dying trees, the city adopted a policy to replace all sick trees with sycamore trees.

Which of the following, if true, would most weaken the logic employed by the city planners?

a) In the forest, oak trees live an average of 70 years while sycamore trees only live for an average of 50 years.
b) Automobile manufacturers are developing newer car models that emit significantly fewer pollutants.
c) A survey by Urban Forests found that the sycamore is the most common tree in American cities.
d) The city recently installed low exhaust buses for its public transportation system.
e) Sycamore trees are extremely sensitive to sulfur dioxide, the main component of acid rain.

[spoiler]OA is E, but why not C. Infact the stimulus never mentions anything about acid rain so isn't E out of scope.[/spoiler]

AIM GMAT wrote:I also picked C at first place.

Below is the link with expert comments : -

https://www.beatthegmat.com/kaplan-cr-qu ... 46835.html

Hope that helps .

PostTue Oct 20, 2009 3:33 am Thank this user for their post
The first sentence tells us that "many of the trees in the city were dying because of exposure to increased levels of air and water pollution."

Notice that this is pretty general. We don't know what in the air or water is hurting the trees. Fine, carbon monoxide is good for these trees. But if the problem in the air or water pollution is something that cannot be remedied by elevated levels of carbon monoxide, then the plan will fail (b/c it would have failed to target the cause of the problem). In other words, the plan assume that the beneficial agent (carbon monoxide) will target the cause of the problem.

E is a fact which, if true, suggests that the cause of the problem (sulfur dioxide) is something that the elevated carbon monoxide will fail to remedy. Thus, we should now find it less believable that the plan will work.


Instead of weakening "the logic of the plan", choices b and d are facts which suggest the plan may not work as well as they thought it would had their logic been correct.