Logical reasoning PrepTest 149 · Section 4 · Question 6

Incorrect. If this GRB is a one-off, then the classifications could still be useful. If anything, this answer cuts against the argument.

Incorrect. If the duration can sometimes be used to properly classify a GRB, then the descriptive system based on length still has a use.

Correct. Argument or Facts:
Argument

Valid or Flawed:
Flawed

Question Type:
Strengthen

Stimulus Summary:
GRB classification is based on duration—"short" or "long." However, a new GRB was long, but had all the other characteristics of a short GRB. Therefore, using duration labels is no longer useful.

Answer Anticipation:
The argument here is rather strong—that the descriptive labels based on duration have "outlived their usefulness"—i.e., they're no longer useful. However, even the unusual GRB could be classified using the traditional system. There's no indication that these other features are more important than the duration. Or that the unusual GRB isn't a weird one-off, and that the old system is still useful for 99% of GRBs. The correct answer, therefore, should either highlight the importance of the other factors in classifying GRBs, or establish that a classification system that has trouble with a single example isn't useful, or that the unusual GRB is representative of a newly discovered type of GRB that's prevalent.

Answer Explanation:
If the properties other than duration are more important than duration in categorizing this unusual GRB, then that calls the usefulness of the traditional classification system based on duration into question. While it doesn't prove that it's useless, it does suggest that, at least in this new case, it's not the proper way to classify GRBs, thus opening the door to all GRBs being classified based on other properties.

Key Takeaway:
Remember that Strengthen questions just ask you to get the argument closer to valid, not all the way. Anything that opens the door even a little bit will be a correct answer!

Incorrect. Normally, eliminating an alternative possibility would strengthen the remaining ones. However, this argument concludes that one classification method is useless because of one example that doesn't clearly align with it, so ruling out this alternative that isn't clearly indicated in the stimulus is out of scope.

Incorrect. Replacing the labels doesn't get at the problem presented by the unusual GRB—it has something in common with GRBs from both classifications. Without addressing that, this answer doesn't affect the argument.