Text 1In 2021, a team led by Amir Siraj hypothesized that the Chicxulub impactor—the object that struck the Yucatán Peninsula...
GMAT Craft and Structure : (Structure) Questions
In 2021, a team led by Amir Siraj hypothesized that the Chicxulub impactor—the object that struck the Yucatán Peninsula sixty-six million years ago, precipitating the mass extinction of the dinosaurs—was likely a member of the class of long-period comets. As evidence, Siraj cited the carbonaceous chondritic composition of samples from the Chicxulub impact crater as well as of samples obtained from long-period comet Wild 2 in 2006.
Text 2Although long-period comets contain carbonaceous chondrites, asteroids are similarly rich in these materials. Furthermore, some asteroids are rich in iridium, as Natalia Artemieva points out, whereas long-period comets are not. Given the prevalence of iridium at the crater and, more broadly, in geological layers deposited worldwide following the impact, Artemieva argues that an asteroid is a more plausible candidate for the Chicxulub impactor.
Based on the texts, how would Artemieva likely respond to Siraj's hypothesis, as presented in Text 1?
By insisting that it overestimates how representative Wild 2 is of long-period comets as a class
By arguing that it does not account for the amount of iridium found in geological layers dating to the Chicxulub impact
By praising it for connecting the composition of Chicxulub crater samples to the composition of certain asteroids
By concurring that carbonaceous chondrites are prevalent in soil samples from sites distant from the Chicxulub crater
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| Text 1 | |
| "In 2021, a team led by Amir Siraj hypothesized that the Chicxulub impactor—the object that struck the Yucatan Peninsula sixty-six million years ago, precipitating the mass extinction of the dinosaurs—was likely a member of the class of long-period comets." |
|
| "As evidence, Siraj cited the carbonaceous chondritic composition of samples from the Chicxulub impact crater as well as of samples obtained from long-period comet Wild 2 in 2006." |
|
| Text 2 | |
| "Although long-period comets contain carbonaceous chondrites, asteroids are similarly rich in these materials." |
|
| "Furthermore, some asteroids are rich in iridium, as Natalia Artemieva points out, whereas long-period comets are not." |
|
| "Given the prevalence of iridium at the crater and, more broadly, in geological layers deposited worldwide following the impact, Artemieva argues that an asteroid is a more plausible candidate for the Chicxulub impactor." |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Two scientists disagree about whether the Chicxulub impactor was a comet (Siraj) or an asteroid (Artemieva), with each using different compositional evidence to support their hypothesis.
Argument Flow: Siraj bases his comet hypothesis on shared carbonaceous chondrite composition, but Artemieva counters that this evidence isn't unique to comets and points to the prevalence of iridium (found in asteroids but not comets) as stronger evidence for an asteroid impact.
Step 2: Interpret the Question Precisely
What's being asked? How would Artemieva likely respond to Siraj's hypothesis specifically
What type of answer do we need? Artemieva's reaction/critique of Siraj's reasoning
Any limiting keywords? Artemieva's likely response based on the passage content
Step 3: Prethink the Answer
- From our analysis, Artemieva disagrees with Siraj's comet hypothesis
- Her main points are:
- Siraj's evidence (carbonaceous chondrites) isn't unique to comets—asteroids have them too
- There's better evidence pointing to asteroids: the iridium found at the crater and in global geological layers
- Asteroids contain iridium while long-period comets don't
- So the right answer should reflect Artemieva pointing out a weakness in Siraj's evidence or highlighting evidence that Siraj didn't consider—specifically the iridium evidence that better supports an asteroid hypothesis
By insisting that it overestimates how representative Wild 2 is of long-period comets as a class
- This focuses on whether Wild 2 represents all long-period comets
- Artemieva never questions the representativeness of Wild 2 as a comet sample
- Her argument isn't about comet sampling—it's about the evidence itself
By arguing that it does not account for the amount of iridium found in geological layers dating to the Chicxulub impact
- This directly matches Artemieva's argument from our analysis
- She specifically points to iridium prevalence at the crater and in worldwide geological layers
- Her whole argument is that Siraj's hypothesis fails to account for this crucial iridium evidence
By praising it for connecting the composition of Chicxulub crater samples to the composition of certain asteroids
- Artemieva never praises Siraj's work or connects crater samples to asteroids
- She's arguing against his hypothesis, not praising any aspect of it
By concurring that carbonaceous chondrites are prevalent in soil samples from sites distant from the Chicxulub crater
- Artemieva doesn't discuss carbonaceous chondrites in distant soil samples
- She acknowledges that both comets and asteroids have carbonaceous chondrites, but that's not her main point