Logical reasoning PrepTest 118 · Section 1 · Question 2

Incorrect. The frequency of these disruptions isn't important to the argument—instead, the impact on humans when they happen is. (Note that extraterrestrial means outside Earth, not based on little green men or ET.)

Incorrect. First, the ozone layer being damaged by natural events as a normal occurrence is a part of the Commentator's argument, so this answer aligns with it. Second, it doesn't connect to harm, or to the premises in the argument—another reason it doesn't affect the argument.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Weaken

Stimulus Summary:
CFCs damage the ozone layer and let in more UV radiation, but a supernova did the same to much larger effect 300,000 years ago and it didn't hurt our ancestors, so this damage today isn't a threat to us.

Answer Anticipation:
This argument relies on humans 300,000 years ago being relevantly similar to humans today in order to draw its conclusion. Is that a good assumption? We don't know! We're not evolutionary biologists or geneticists, so we can't say. But the Commentator also doesn't establish that we are relevantly similar, so an answer highlighting a relevant difference will weaken this argument.

Answer Explanation:
This answer highlights a relevant difference between these early humans and modern ones. If those earlier humans were genetically more resistant to damage from UV radiation, then the impact the damage to the ozone layer had on them is no longer good proof for how it'll impact us today.

Key Takeaway:
When a Weaken question is based on treating two things as comparable, then relevant differences between the two will be a correct answer.

Incorrect. The argument doesn't discuss timelines or recovery from ozone damage, so this answer is out of scope.

Incorrect. This answer either calls a premise into question (the lack of effect on our ancestors), or it brings up an insignificant change (since the premise states there were no significant effects from the supernova). In either case, it doesn't address the question.