Just ARGUE. That's all you have to do. The conclusion in Question #5, Section 3 of the June 2007 LSAT is "the ants were not bringing food to their neighbors." The evidence is "the ants were emptying their own colony's dumping site." The problem with this logic is that it's possible that the ants were feeding their garbage to their neighbors.
That's nasty, but it's possible. If it were true, the argument would make no sense. Since I've identified the huge hole in the argument, I've already answered the question--even though I haven't seen what the question actually asks yet.
The question says "Atrens's conclusion follows logically if which one of the following is assumed?" This is a Sufficient Assumption question.
I've done a lot of writing about Sufficient Assumptions recently: Here's what "sufficient" means. And here's what "assumption" means. Put those two together, and here's what "Sufficient Assumption" means. Master the basics and this is a very easy type of question.
Basically, all I have to do is take Atrens's evidence, add one piece of additional evidence (the correct answer) and PROVE the conclusion of Atrens's argument. I can usually predict the answer on a question like this before looking at the answer choices. And I'll always try, because predicting answers makes it a lot easier to avoid traps and distractions.
I think a perfect bridge between Atrens's evidence and Atrens's conclusion would be "no creature feeds its garbage to its neighbors." If that's true, then the hole in Atrens's argument has been perfectly plugged. Let's see if that's it.
A) This isn't what I'm looking for. And I don't see how, if it were true, it would prove that the ants weren't feeding garbage to their neighbors. (Humans don't feed garbage to their neighbors, do they?)
B) Again, not what I'm looking for. This is a problematic answer because if there is "only weak evidence" that means there IS some evidence which may or may not be good. This is so wishy-washy that I doubt it could be used to conclusively PROVE anything.
C) This is it. If this is true, then ants can't be feeding their garbage to their neighbors. I'm almost positive this will be our answer. Let's just glance and D and E to make sure one of them doesn't look really attractive.
D) Nah. This wouldn't prove that the ants aren't receiving garbage as food.
E) No, it's not relevant whether the entymologist retracted his conclusion. The only thing that's relevant is whether the entomologist was right or wrong. (You can retract a position that is wrong, or retract a position that is right.) Our answer is C, because if it is true then it PROVES Atrens's conclusion.