All oceangoing ships carry

Answer choices

1. A

   Too Strong: ensure17% picked this

   Emptying and refilling an oceangoing ship’s ballast tanks in midocean would ensure at least that no sea creatures capable of disturbing the ecology in

   This would be a great strengthener, but it's stronger than what the author needs to assume. She only said that the species-swapping that would be happening in her plan involved creatures who usually cannot survive in one another's habitats. The author is only assuming that emptying and refilling in midocean would reduce the chances of pumping into the tanks some sea creature that was capable of disturbing the ecology in a new habitat. She hasn't committed to the idea that her plan perfectly prevents the problem from occurring.

   17%
2. B

   Too Strong: only Weakens2% picked this

   An oceangoing ship’s ballast tanks could be emptied and refilled in midocean only in conditions of calm

   This is actually a knock against the plan. It doesn't sound like as viable a plan if the ships have to wait for conditions of calm air and flat seas. As written it would weaken, so an author would never be needing to assume something that weakens their argument. It's also so restrictive (they could do it only in certain conditions), that it goes beyond the strength of anything our author said.

   2%
3. C

   Out of Scope: most historical cases16% picked this

   Sea creatures have rarely, if ever, wreaked ecological havoc in a new habitat, unless they have been able to survive in that habitat after

   This answer is very tempting, since the author is assuming if these sea creatures they are less likely to can't survive in the → wreak havoc than other's habitat currently is the case This answer looks like a contrapositive of that, sorta: wasn't the case that a usually would not sea creature survived → wreak havoc in in new habitat after the new habitat having been dumped by a ship The easiest way to distance ourselves from this is to notice that it's addressing a past tense historical fact. The author isn't assuming anything about the past. She's pitching us a supposedly viable plan we could try in the future, so her assumptions are about what would be true in the hypothetical world in which we tried her plan. This answer is about what has been true in the actual world we live in. If we fixed the tense (sea creatures will rarely, if ever, wreak havoc .... ), this answer still would struggle. When we negate it, we get this: Sea creatures have frequently wreaked ecological havoc in a new habitat, without the backstory of surviving in the new habitat after having been deposited there by ships. In simpler terms, the negation would be saying, "Sea creatures have frequently messed up a new habitat for a reason separate from the problem the author is trying to solve". Okay, would that weaken the argument? No, because the author isn't saying her midocean solution will prevent all or most cases of sea creatures messing up a new habitat they're in. She's just saying it's a viable way to address the part of that problem caused by ships dumping their ballast water.

   16%
4. D

   Too Strong5% picked this

   Currently, seawater is pumped into or out of the ballast tanks of oceangoing ships to maintain proper stability only

   Too Strong: only Only Thing Mentioned ≠ Only Thing Trap answers on Necessary Assumption love to take the only thing an author mentioned and then act like it's the only thing that has that property. Like if I said, "There are some girls in my class that wear earrings", it would accuse me of assuming, "Only the girls in the class wear earrings". Here, it told us that "to maintain stability, water is pumped in and out of ballasts", so there's a trap answer saying, "the only time water is pumped in and out is to maintain stability". If we negated this and said that there are other times too when seawater is pumped in or out, that wouldn't hurt the author's argument at all.

   5%
5. E

   Correct59% picked this

   There are at least some oceangoing ships whose stability could be adequately maintained while emptying and refilling their

   Why this is right

   This is something that needs to be true for the author's Plan to be feasible, and therefore it's required in order for her plan to be "viable". If we negate this (contradicting at least one = none) There are no oceangoing ships whose stability could be adequately maintained while performing the move the author proposed. That doesn't sound like a viable plan to me anymore. There are no ships that can adequately maintain stability to pull it off.

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

   59%