#4 - In an experiment testing whether hyperactivity is due to a brain abnormality

[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!

[kcho10]

Hi,

I'm not sure why E doesn't weaken the argument. I can see why D weakens more than E, but the LSAC explanation makes it seem like it doesn't weak then argument at all. E says that the test was performed only on adults. Doesn't that suggest that it's an unrepresentative sample? The conclusion doesn't confine the scope of the argument to adults only.

Thank you in advance

[Jennifer Janowsky]

Hi! Great question. Answer choice (E) points out that only adults were considered, which is an interesting point as it calls into question the research group. However, the fact that the result was found in adults alone doesn't immediately hurt the conclusion that "diminished activity is one cause of hyperactivity." Alternately, choice (D) much more directly harms that conclusion--it presents an alternate cause, their medication, for their decreased brain activity.

So, as you said, answer choice (E) does seem to indirectly weaken the conclusion, whereas (D) does so much more directly and to a greater degree.

I hope that is helpful!