mivas
VeritasKarishmaB does make sense. But I eliminated it because it seems to challenge the premise. My understanding is that the premise in GMAT is to be taken as truth and not to be questioned. In this particular question, there is no other option besides B which make sense. But in general(For actual Gmat questions) is it a good strategy to reject answer choices that are questioning the truth of the premise?
mivasOption (B) does not challenge any premise.
B. The person examining the tile for evidence of spilled punch has been able to detect such evidence in considerably more obscure, hidden places.
It tells us that the examiner is skilled at detecting spillage. He has been able to detect even in cases when it was more difficult to detect, say when spillage was hidden or inside a crack etc.
Here he was not able to detect any spillage increases the likelihood that there was no spillage. When an expert could not detect it, it does make it more likely that no spillage happened (but doesn't prove beyond doubt).
Since we want to strengthen our argument, knowing that the examiner is an expert strengthens it.