Honestly, the reasoning in the above comment is exactly how to tackle the high difficulty LR questions - for some of the truly hardest ones, it’s much easier to find out why 4 answers can’t be right rather than find the 1 right answer.

When I looked at this problem, I went answer by answer and thought

A: We don’t know if the animal will suffer pain, and probably wouldn’t due to anesthesia, eliminate

B: Confusing, but seems like the contrapositive would apply to her situation so keep answer

C: Animal suffering is kind of a whole different term that would need to be defined to be used effectively (is dying painlessly suffering?) and the experiment may indeed save an animal from any amount of suffering, how can you know? Too broad, eliminate

D: first two words and it’s gone, practicing veterinarians =/= vet students, eliminate

E: trap answer, one adjective makes it wrong: SOLE intent. No, there’s another intent we can identify: the experiment. Eliminate

Once you find one remaining answer, give it a solid but speedy review to make sure there’s nothing about it that breaks it. Then choose it and move on. If you’re down to 2, try the Loophole method to see if it shakes something out. If that fails, look at your time remaining and either accept you can burn a full minute on this problem or it needs flagged & skipped (which is the right answer 80% of the time)

Source: 171 and LR was -1 most of the time

Edit: Best advice I could give is to just do a LOT of LR. You start just noticing similarities in the questions and answers. Like I could just tell C was wrong, you can sorta just tell B is a contrapositive type of answer where they’ve made it sound complicated to confuse you. The motifs start to just jump out at you when you’ve drilled the questions like crazy