Delta green ground beetles sometimes remain motionless for hours at a stretch, although they are more active in wet y...

shunhe on October 2, 2020

Hi @juliagutierrez,

Thanks for the question! So let’s take a look at what this stimulus says first. We’re told that these delta green ground beetles can sometimes be motionless for hours at a time, but they’re more active in wet years than dry years. In 1989, someone say 10 DGG beetles in 9 hours; in 1985, the same person counted 38. But, the argument concludes, it’s probably not a population drop. Why? Because 1985 was a wet year, and 1989 was a drier year.

Now we’re asked for something that most strongly supports the conclusion drawn above. Remember, the conclusion rain above is that the difference probably doesn’t reflect a population drop. So let’s take a look at (B), which says that the only habitat of DGG beetles is around pools formed by the collection of winter rains in low lying areas. OK, how does that help us conclude that the top in population isn’t the reason for the 1989 numbers being lower? In fact, (B) might suggest that since 1989 was drier, and their habitats were smaller, there would be fewer beetles. But that would make us think that the population did go down, and that weakens the argument.

(A), on the other hand, tells us that because of their excellent camouflage, DGG beetles are almost impossible to see if they’re not moving. Well, if that’s true, then we can only see the moving ones. And they move more when it’s wet. So that helps us think that it’s not a population drop, it strengthens the argument! And that makes (A) correct.

Hope this helps! Feel free to ask any other questions that you might have.