#14 - Caffeine can kill or inhibit the growth of the larvae

[maximbasu]

Hello,
I chose D as the correct answer while the correct answer was E.

Is D just simply out of scope, irrelevant?

I didn't chose E because I reasoned that it was out of scope because it covers a time period not mentioned in the stimulus. The stimulus states "evolved as a defense." I'm guessing the time period of the ancestors is covered by the word "evolved" then.

Thank you, Maxim.

[Adam Tyson]

In short, yes - good guess! Instead of guessing, though, try the negation technique on those two answers, and you will find that E, when negated, destroys the argument. If caffeine-sensitive creatures never ate those plants, then the plants would not have evolved to include caffeine as a defense.

[jlam061695]

If we do the negation technique on C (caffeine-producting plants grow in places where insect larvae DO NOT pose a major threat to indigenous plants), then wouldn't it also weaken the conclusion that caffeine evolved as a defense for those plants?Because if caffeine-producing plants grew in non-plant-threatening larvae areas, then they wouldn't necessarily use the caffeine gene for as a defense mechanism against the larvae.

[Adam Tyson]

That's not how I would have negated answer C, jlam - my choice would be "caffeine producing plants don't grow everywhere that larvae pose a major threat" - but in either case our negations don't do nearly as much damage to the argument as the negation of the correct answer, E, does.

One problem I have with C is the use of the word "major". Who says it has to be a major threat? Maybe they produce caffeine in response to minor threats, too?

Another problem I have with C is that the argument is not an absolute causal claim, but is qualified by "various" and "many". In other words, some plants do this (but not necessarily all). Our author has hedged his bets on this causal connection, so attacking it in the usual way won't work so well. This defense mechanism doesn't have to crop up everywhere the threat exists, just somewhere.

Negate E and you crush the argument. That makes it the best answer, and that's the best reason for not selecting C.