PrepTest 102

Incorrect. The conclusion is about dwarf masked owls, so this answer about other birds of prey is out of scope.

Incorrect. The conclusion treats the spiny cacti as necessary for dwarf owls to summer in Baja (unless cacti, no owls/not Cacti → not Owl/Owl → Cacti), so it doesn't rely on them being sufficient to get the owls there, as this answer states.

Incorrect. The conclusion does rely on there being another place for the dwarf masked owl to winter, but that location doesn't have to be "far from" it's migratory route—it could be close to that route, just not in Baja.

Incorrect. Based on the work we did in (B), we can see that this answer (not Owl → not Cacti) is the negation of the conclusion, so it's not a necessary assumption.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Dwarf masked owl - Winters in Baja, nesting on spiny cacti
Problem - All the spiny cacti in Baja were destroyed
Conclusion - If the cacti aren't regrown, the owls won't winter in Baja

Answer Anticipation:
The conclusion here? No cacti, no dwarf masked owls in Baja this winter.

Why does the argument believe that? Because the cacti are where the dwarf masked owls make their nests.

However, there's no indication that the lack of nesting sites/cacti would result in the dwarf masked owls skipping Baja this winter. Maybe they wouldn't know that the cacti were missing until they'd show up, and at that point, they're stuck. Maybe they'd just chill out on the beach, not making nests this year.

Any answer that deals with this assumption—no nests, no dwarf owls wintering—should be considered here.

Answer Explanation:
This answer reflects the assumption we identified in the argument. If nesting sites don't need to be present where the dwarf masked owl winters, then they may nest in Baja even if the cacti aren't reestablished. This negation kills the argument, so this is a necessary premise.

Key Takeaway:
Note that we had two answers here that "messed up" the conditional logic of the conclusion. When an answer is a reversal/negation of the conclusion in a Strengthen with Necessary Premise question, you can eliminate it immediately.