No chordates are tracheophytes,

Answer choices

1. A

   Unrelated to Goal3% picked this

   All members of the family Hominadae

   This isn't giving us H --> C (or ~C --> ~H). From our evidence we have, P ---> T ---> ~C This answer says, H --> T. That doesn't chain onto our evidence at all, other than that we could write. H or P ---> T ---> ~C So have we derived the conclusion? P --------------> ~H No, not even close.

   3%
2. B

   Correct63% picked this

   All members of the family Hominidae

   Why this is right

   This is what we were looking for: H → C (or ~C → ~H) From our evidence we had, P → T → ~C This answer says, ~C → ~H We can chain that onto our evidence to get P → T → ~C → ~H So have we derived the conclusion? P --------------> ~H Yes!

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

   63%
3. C

   Unrelated to Goal3% picked this

   All tracheophytes are members of

   The answer has to talk about H, since H only appears in the conclusion. We can't derive a claim about H if we have no facts (i.e. premises + answer choice) that contain H in them. Any answer choice without H is immediately useless on this problem. Because T and P have already been mentioned multiple times in the argument, we would not think that they are part of the missing link. So if we were just guessing, we'd avoid answers with T or P. Ultimately every wrong answer on Sufficient Assumption is wrong for the same reason: it fails to prove the conclusion. From our evidence we knew, P ---> T ---> ~C This answer says, T --> P. That doesn't chain onto our evidence at all, other than that we could write. P <---> T ---> ~C Does that allow us to prove this conclusion? P --------------> ~H No, because our facts don't include H at all. Who's H? We can't derive a claim about H if we have zero facts (i.e. premises + answer choice) that talk about H.

   3%
4. D

   Trap14% picked this

   No members of the family Hominidae

   14%
5. E

   Unrelated to Goal Already Known17% picked this

   No chordates are members of

   The answer has to talk about H, since H only appears in the conclusion. We can't derive a claim about H if we have no facts (i.e. premises + answer choice) that contain H in them. Any answer choice without H is immediately useless on this problem. This answer also repeats something we already knew. From our evidence we knew, P → T → ~C contrapositive, C → ~T → ~P This answer says, C → ~P. So this answer is just telling us about the beginning/end of the chain we got when we linked up the two premises. We can read our own chain, (E). We already knew that C → ~P. Since this answer provides no new information, it can't possibly be right.

   17%