#12 - Ecologist: El Niño, a global weather phenomenon that occurs once every several years,

[Administrator]

Complete Question Explanation

Weaken. The correct answer choice is (D).

Answer choice (A):

Answer choice (B):

Answer choice (C):

Answer choice (D): This is the correct answer choice.

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[nicizle]

This question has me confused, even more so because I was confident in my answer until I reviewed. I originally picked C and am genuinely confused as to how this is incorrect. Is this a case of where C and D both weaken, but that D just weakens more? Is there something I'm missing with regard to C that would actually make it a strengthener or have no impact on the argument?

Please help.

[Luke Haqq]

Hi nicizle!

As I understand answer choice (C), it wouldn't in the end have an impact on the argument. Note that the argument's conclusion is in the final sentence of the stimulus: "it is likely that average rodent populations in region T will also increase in coming decades." We want an answer choice that weakens this conclusion that is specifically about region T.

I can see how it might seem to be a contender because it makes a comparison to another place, but in the end, that doesn't quite weaken a conclusion that is just about region T. What seems especially crucial in this stimulus is a shift from "heavy ... rainfall" to "long periods of sustained rain." Heavy rainfall doesn't necessarily mean long periods of sustained rain. That's what answer choice (D) gets at--it's saying that winters in region T marked by relatively high rainfall have usually not been marked by long periods of sustained rain. If that were true, then the cause of rodent population increases would be missing, which weakens the conclusion.