Until about 400 million years ago,

Answer choices

1. A

   Too Strong: primary / all1% picked this

   Fish are the primary prey of all

   We actually don't know if fish are the prey of any jawed fishes, let alone the primary prey of all jawed fishes. The stimulus just tells us that "jawed fishes could actively pursue prey". We have no idea what type of prey.

   1%
2. B

   Correct66% picked this

   The jawless fishes did not prey upon

   Why this is right

   This can be derived from the first two sentences (making it highly obnoxious that we had to read and worry about the rest of that paragraph!). We were told that the jawless fishes' feeding methods were limited to sucking in surface plankton or sucking in food particles from bottom mud. So that means they weren't preying upon other fish, just suckin' up plankton from the roof or food particles from the floor. While those two claims are enough to justify this answer, this answer also reinforces the Pivot + Causal Difference-Maker. We were told that, "once they developed biting jaws, however, this allowed them to pursue prey". So this answer is a form of the classic Flip the Causal Difference-Maker inference, in which we say, "If jaws enabled them to pursue prey, then when they were jaw-less, they did not have the ability to pursue prey."

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

   66%
3. C

   Too Strong: do not7% picked this

   Teleosts do not feed upon particles found in

   We know that teleosts are not limited to feeding on the bottom mud. Their biting jaws allow them to pursue prey, but we were never told that they exclusively pursue prey. Someone's increased income might allow them to eat out at nicer restaurants; they used to be limited to McDonald's and other fast food, but their pay raise allows them to dine at fast causal or even sit-down restaurants. But that doesn't mean they never get a hankering for a Big Mac (which, by metaphor, in this case, is the particles found in bottom mud / sorry, McDonald's). Similarly, when times are tough and prey can't be found, or maybe just when they're feeling snacky, it's highly possible that teleosts still feed on particles found in bottom mud.

   7%
4. D

   Opposite19% picked this

   Jawless fishes did not have cartilage as their

   We could probably infer that jawless fishes didn't have bone as their skeletal material. We're told then after jaws developed, the jawed fishes broke into two main lines: one retained cartilage, the other adopted bone. So that implies that the status quo was cartilage skeletons. The bony fish were the ones who innovated a new evolutionary path after jaws had already evolved.

   19%
5. E

   Too Strong: extinct7% picked this

   Jawless fishes became extinct approximately 400 million

   We're told that around 400 million years ago, some fish started to have jaws. That doesn't mean that jawless fish were suddenly out of existence. Evolution takes a lot of time. It might take millions of years for jawed fishes to outcompete and out-replicated jawless fishes. But it's also possible that jawless fishes are still alive today. Nothing in the stimulus indicates they ever went extinct.

   7%