PrepTest 149

Incorrect. This answer undermines the argument by suggesting that elements prevalent in the early solar system wouldn't be present in meteorites, so meteorites aren't a good way to measure early solar system elements.

Incorrect. Even if other solar systems were formed by dust and gas from supernovae, the lack of iron-60 in meteorites from this solar system could still disprove that mechanism as the way our solar system formed.

Incorrect. Other types of iron are out of scope of the argument, as they're unmentioned and can't be directly related to any of the ideas in the stimulus.

Incorrect. The stimulus is very clear that the necessary condition for the hypothesis being correct is that iron-60 was in the early solar system, so what is true of meteorites formed much later is out of scope.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen with Necessary Premise

Stimulus Summary:
Hypothesis correct → Iron-60 in early solar system
But researchers haven't found iron-60 in meteorites from then
So the hypothesis is wrong

Answer Anticipation:
The argument does set up a condition under which we could conclude that the hypothesis is incorrect—there being no iron-60 in the early solar system. However, the argument doesn't establish that there was no iron-60 in the early solar system—just that we haven't detected iron-60 in meteorites formed in that time period. The correct answer, then, will connect those two, stating that if iron-60 were present in the early solar system, we'd see it in meteorites from then.

Answer Explanation:
This answer connects iron-60 in the early solar system to iron-60 in meteorites formed at that time, which is the missing connection from the stimulus. If iron-60 in the early solar system wouldn't be found in meteorites formed then, then the stimulus using that as a measurement to establish there was no iron-60 in the early solar system is flawed and the argument falls apart.

Key Takeaway:
Often when a sufficient condition to reach a conclusion appears to be met by a premise, there's a term shift that makes the argument flawed. Always check the premise against the sufficient condition to make sure there are no gaps and, if there are, use that to help you find the correct answer!