Astronomer: Observations of the Shoemaker-Levi comet on its collision course with Jupiter showed that the comet broke into fragments before...

GMAT Critical Reasoning : (CR) Questions

Source: Official Guide

Critical Reasoning

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Astronomer: Observations of the Shoemaker-Levi comet on its collision course with Jupiter showed that the comet broke into fragments before entering Jupiter's atmosphere in 1994, but they did not show how big those fragments were. In hopes of gaining some indication of the fragments' size, astronomers studied spectrographic analyses of Jupiter's outer atmosphere. These analyses revealed unprecedented traces of sulfur after the fragments' entry. The fragments themselves almost certainly contained no sulfur, but many astronomers believe that the cloud layer below Jupiter's outer atmosphere does contain sulfur. Since sulfur would have seeped into the outer atmosphere if comet fragments had penetrated this cloud layer, it is likely that some of the fragments were at least large enough to have passed through Jupiter's outer atmosphere without being burned up.

In the astronomer's argument, the two portions in boldface play which of the following roles?

The first presents a circumstance for which the astronomer offers an explanation; the second is part of that explanation.

The first acknowledges a consideration that weighs against the conclusion of the argument; the second is that conclusion.

The first acknowledges a consideration that weighs against the conclusion of the argument; the second provides evidence in support of that conclusion.

The first provides evidence in support of the conclusion of the argument; the second acknowledges a consideration that weighs against that conclusion.

The first is a judgment advanced in support of the conclusion of the argument; the second is that conclusion.

Solution

Understanding the Passage

Text from Passage	Analysis
"Observations of the Shoemaker-Levi comet on its collision course with Jupiter showed that the comet broke into fragments before entering Jupiter's atmosphere in 1994, but they did not show how big those fragments were."	What it says: Scientists observed a comet breaking apart before hitting Jupiter in 1994, but couldn't determine the size of the pieces. Visualization: Comet breaks into fragments: Maybe 10 pieces? 100 pieces? Scientists know fragments exist but don't know if pieces were 50 meters wide or 5000 meters wide. What it does: Sets up the scientific problem - we have incomplete information about fragment sizes. Source: Author's statement of established facts
"In hopes of gaining some indication of the fragments' size, astronomers studied spectrographic analyses of Jupiter's outer atmosphere."	What it says: To figure out fragment sizes, scientists analyzed Jupiter's atmosphere using spectroscopy. Visualization: Scientists think: "If we study Jupiter's atmosphere after impact, maybe we can work backwards to determine fragment sizes." What it does: Explains the research method chosen to solve the problem. Source: Author's description of scientific approach
"These analyses revealed unprecedented traces of sulfur after the fragments' entry."	What it says: The atmospheric studies found sulfur traces that had never been detected before in Jupiter's outer atmosphere. Visualization: Before impact: 0% sulfur detected in outer atmosphere → After impact: Sulfur traces detected for first time ever What it does: Provides the key evidence that needs explanation. Source: Author's statement of research findings
"(Boldface 1) The fragments themselves almost certainly contained no sulfur"	What it says: The comet pieces definitely didn't have sulfur in them. Visualization: Comet fragments: 0% sulfur content vs. Jupiter's atmosphere after impact: Sulfur detected What it does: Rules out one possible explanation for the sulfur traces - eliminates the idea that sulfur came from the comet itself. Source: Author's definitive statement
"but many astronomers believe that the cloud layer below Jupiter's outer atmosphere does contain sulfur."	What it says: Scientists think there's sulfur in Jupiter's inner cloud layers, deeper than the outer atmosphere. Visualization: Jupiter's structure: Outer atmosphere (normally 0% sulfur) → Cloud layer below (contains sulfur) → Deeper layers What it does: Introduces an alternative source for the sulfur - Jupiter's own internal layers. Source: Other astronomers' belief
"Since sulfur would have seeped into the outer atmosphere if comet fragments had penetrated this cloud layer"	What it says: If fragments went deep enough to reach the sulfur-containing cloud layer, sulfur would leak upward into the outer atmosphere. Visualization: Fragment impact scenario: Fragment penetrates through outer atmosphere → Reaches sulfur-rich cloud layer → Sulfur seeps upward from cloud layer to outer atmosphere What it does: Establishes the logical connection between fragment penetration depth and sulfur detection. Source: Author's logical reasoning
"(Boldface 2) it is likely that some of the fragments were at least large enough to have passed through Jupiter's outer atmosphere without being burned up."	What it says: Some fragments were probably big enough to survive passing through Jupiter's outer atmosphere without being destroyed. Visualization: Fragment size implications: Small fragments (maybe 50 meters) → Burn up in outer atmosphere, never reach cloud layer → Large fragments (maybe 5000 meters) → Survive outer atmosphere, reach sulfur-containing cloud layer What it does: Draws the final conclusion about fragment sizes based on the sulfur evidence. Source: Author's conclusion

Overall Structure

The author is building a logical argument to determine comet fragment sizes using indirect evidence. The flow is: Problem (unknown fragment sizes) → Research method (atmospheric analysis) → Evidence (sulfur detected) → Explanation (sulfur came from Jupiter's internal layers, accessed by fragments) → Conclusion (fragments were large enough to penetrate deeply).

Main Conclusion: It is likely that some of the fragments were at least large enough to have passed through Jupiter's outer atmosphere without being burned up.

Boldface Segments

Boldface 1: The fragments themselves almost certainly contained no sulfur
Boldface 2: it is likely that some of the fragments were at least large enough to have passed through Jupiter's outer atmosphere without being burned up

Boldface Understanding

Boldface 1:

Function: Rules out the possibility that sulfur came from the comet fragments themselves, eliminating one potential explanation for the sulfur detection
Direction: Supports the author's conclusion by eliminating alternative explanations and forcing consideration of Jupiter's internal sulfur as the source

Boldface 2:

Function: States the main conclusion about fragment sizes based on the logical chain of evidence
Direction: This IS the author's ultimate conclusion, so it definitively supports the author's position

Structural Classification

Boldface 1:

Structural Role: Supporting premise that eliminates alternative explanations
Predicted Answer Patterns: "eliminates a potential explanation," "rules out an alternative source," "supports the argument by elimination"

Boldface 2:

Structural Role: Main conclusion of the argument
Predicted Answer Patterns: "main conclusion," "final inference," "what the argument concludes"

Answer Choices Explained

The first presents a circumstance for which the astronomer offers an explanation; the second is part of that explanation.

'The first presents a circumstance for which the astronomer offers an explanation' - ✗ WRONG - Boldface 1 doesn't present a circumstance needing explanation; it eliminates a potential explanation for the sulfur detection
'the second is part of that explanation' - ✗ WRONG - Boldface 2 is the conclusion, not part of an explanation

The first acknowledges a consideration that weighs against the conclusion of the argument; the second is that conclusion.

'The first acknowledges a consideration that weighs against the conclusion of the argument' - ✗ WRONG - Boldface 1 actually supports the conclusion by eliminating alternative explanations, rather than weighing against it
'the second is that conclusion' - ✓ CORRECT - Boldface 2 is indeed the main conclusion of the argument

The first acknowledges a consideration that weighs against the conclusion of the argument; the second provides evidence in support of that conclusion.

'The first acknowledges a consideration that weighs against the conclusion of the argument' - ✗ WRONG - Same error as Choice B; Boldface 1 supports rather than opposes the conclusion
'the second provides evidence in support of that conclusion' - ✗ WRONG - Boldface 2 IS the conclusion, not evidence supporting it

The first provides evidence in support of the conclusion of the argument; the second acknowledges a consideration that weighs against that conclusion.

'The first provides evidence in support of the conclusion of the argument' - ✓ CORRECT - Boldface 1 does support the conclusion by eliminating alternative explanations
'the second acknowledges a consideration that weighs against that conclusion' - ✗ WRONG - Boldface 2 IS the conclusion, and it doesn't weigh against itself

The first is a judgment advanced in support of the conclusion of the argument; the second is that conclusion.

'The first is a judgment advanced in support of the conclusion of the argument' - ✓ CORRECT - Boldface 1 is indeed a judgment (determining comet fragments contained no sulfur) that supports the conclusion
'the second is that conclusion' - ✓ CORRECT - Boldface 2 is clearly the main conclusion the entire argument builds toward

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