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#8- Delta green ground beetles sometimes remain motionless

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I am wondering why A is the best answer? I crossed it off because since 85 was a wetter year there should be more movement of the beetles compared to a relatively dry year such as 89. Intuitively, this would suggest in my mind that the wetter the season the more you will see the beetle. Therefore, 85 would have more beetles than 89 which is not the case so I crossed A off. Also, can you tell me why B is incorrect? C, D and E are pretty self explanatory of why they are wrong.

Adam Tyson
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I think you may have answered your own question without realizing it, Eric! Your analysis of A is perfect - 85 was wetter, so the beetles were probably moving more and thus easier to spot. That explains why the observer saw so many more in that year than in 89, when they would have been moving less if at all. It looks like maybe you mis-read the stimulus, thinking the opposite occurred, that more were seen in 89 than in 85? Check it again and you will see the reverse is the case - in 85 it was 38 in 2 hours, in 89 it was only 10 in 9 hours.

So why does that make A the right answer? Focus on the conclusion - what is this author trying to prove? It's the beginning of the last sentence of the stimulus - "This difference probably does not reflect a drop in the population of these rare beetles over this period". In other words, he is saying that a drop in the population is likely NOT the reason for the lower number in 89. Per the stem, we want to strengthen that claim, and A does it by giving another explanation (an alternate cause, perhaps?) for the lower number - not that there were fewer beetles, but that there was less movement and thus they weren't as easily spotted.

B is incorrect because it does nothing to help that conclusion, that a drop in population is not the reason for the lower numbers seen in 89. B might actually weaken the argument by suggesting that in 89 the beetle habitat was reduced in size, thus reducing the population (the very thing we want to say did NOT happen). I'm more inclined to say that B simply has no impact - my reaction to it is "so what?" It tells us where their habitat is, but tells us nothing about whether this particular area is such a habitat and nothing about why, other than a population decrease, we saw fewer beetles in 89 than in 85.

Good work! Now just tie your analysis of the answer back to your goal, helping make the conclusion better, and you are home free.
Adam M. Tyson
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