truthfully, still confused... the more and more i look at D and E, the harder it is to remember what the hell i'm looking for and what they're each supposed to match/not match in the stimulus. my mind is mush.
You need to break the argument down:
Premise I: Prehistoric birds were cold-blooded
Premise II: They were cold-blooded because they had growth rings. Growth rings <-> Cold-Blooded
Premise I: Prehistoric birds had dense blood vessels.
Premise II: Dense -> Active, Active -> Warm-Blooded
Does that help? There's a lot of unnecessary fluff in the original prompt, I agree. You shouldn't have to read convoluted language like "unlike modern birds." We couldn't care less about modern birds or previous studies.
"E," again, weakens the first study. The conditional can't be as air-tight as they pitch it. Growth rings can also indicate warm-blooded.
perfect, thanks for trimming off the crap, makes much more sense now!