During its caterpillar stage

Answer choices

1. A

   Correct85% picked this

   Feeding on the Natal grass cycad is the only means by which the leopard magpie moth can make

   Why this is right

   "The only" is strong, and thus a red flag, but also conditional, and thus something we should examine by looking at it conditionally (as well as its contrapositive). "The only" is a sufficient, Left-side indicator word. (only and only if are necessary, Right-side indicator words) So the idea following "the only", a means of making itself unpalatable to predators, would go on the Left of the arrow. a way to make itself feeding on highly unpalatable → the Natal to predators grass cycad When correct answers are conditional, they're usually written in contrapositive form (to be sneaky, to disguise their potential appeal). When we contrapose this one, we get: can't feed on the no means to make Natal grass cycad → itself highly yucky to predators Did the author's argument make that move? Sure. Not explicitly, but that's definitely the intended meaning of how the author goes from thinking, "Oh, no, the plant that gives them their anti-predator toxin is endangered. Thus they are endangered." He must be thinking that without this plant, the moth loses this defense mechanism, and thus the predators will be able to gobble them up to the point where their species will be in danger of surviving. This answer choice is just calling out that first thought, that "without this plant, the moth will lose the defense mechanism of making itself taste yucky." If we negate this answer and say, "the cycad isn't the only way the moth can make itself unpalatable. There is at least one other way to make itself unpalatable", then that would badly weaken the argument, since it would make it seem like the moths aren't so vulnerable to predators all of a sudden.

   Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

   85%
2. B

   Too Strong: any8% picked this

   The leopard magpie moth does not have the speed or the agility to escape from any

   The argument does need to assume that the moth can't just outrun all its predators (and probably even needs to assume it can't outrun most of its predators). But it doesn't need to assume the extreme idea that it can't outrun a single one of its potential predators. This answer looks tempting because it has the "ruling out" word not, which is very common in correct Necessary Assumption answers. If we negate this, it's saying "the moth does have the speed or agility to escape from at least one of its potential predators". That definitely weakens somewhat! It helps us argue that the moth won't be in that bad a situation when it comes to predators, once it loses its ability to lace its body with cycad toxins. But it doesn't weaken as much as the negation of (A), which makes it sound like the moth's situation isn't going to get any worse at all. The negation of (A) makes it sound like when the cycad goes extinct, the moth won't actually be losing its ability to make itself highly unpalatable.

   8%
3. C

   Weakens, if anything2% picked this

   Potential predators of the leopard magpie moth cannot determine from appearance alone whether a moth's body

   This has the lovable ruling-out language "cannot", no let's negate it and see if it weakens: Predators can determine from appearance alone whether a moth's body is laced with the toxin. No, that would actually strengthen. When they cycad runs out, and the moth is now flying around toxin-free, it wouldn't have the temporary protection of its predators assuming that it still tastes nasty like they've always known it to. Instead, this negation is saying they would visually see that the moth wasn't wearing its "yuck suit" anymore, so it would be open season on hunting the moths.

   2%
4. D

   Too Strong: abundant5% picked this

   Leopard magpie moths are not able to locate Natal grass cycads unless those

   This conditional answer would look like this: cycad plants are → moths can't locate not abundant cycad plants Did our author's thinking make that move? No, not really. It made a move that looked more like this: cycad plants are → moths can't reliably endangered/extinct use toxin-defense

   5%
5. E

   Too Strong: none1% picked this

   None of the potential predators of the leopard magpie moth have developed a

   It wouldn't hurt the author's argument at all if we negated this and said, "at least one of the potential predators has already developed a tolerance for the macrozamin defense mechanism". The author definitely needs to assume that some or even most predators aren't immune to this defense mechanism. After all, if all the predators were already immune to this defense mechanism, then it wouldn't be a functional defense mechanism. So losing it when the cycad goes extinct wouldn't actually change anything in terms of threat from predators. But it's too strong to say the argument needs to assume that not a single one of the potential predators has developed a tolerance for it.

   1%