A subject of much speculation, distinctive sets of parallel ridges mark the icy crust of Europa, Jupiter's smallest moon. Researchers...
GMAT Information and Ideas : (Ideas) Questions
A subject of much speculation, distinctive sets of parallel ridges mark the icy crust of Europa, Jupiter's smallest moon. Researchers now claim that the ridges' formation mechanism mirrors that of a strikingly similar pair on Greenland's ice sheet. There, surface water seeped through fissures in the sheet and formed a water pocket that subsequently disrupted the overlying ice, forcing fragments of it upward and outward into peaks, as the pocket froze and expanded. Although Europa lacks liquid surface water, the same process could be driven by the moon's subsurface ocean.
Which choice best states the main idea of the text?
Researchers think that the ridges on Europa and the ridges in Greenland may have been formed by the same process even though Europa, unlike Greenland, doesn't have liquid water on its surface.
The primary difference between the ridges on Europa and the ridges in Greenland is that unlike the Europa ridges, the Greenland ridges are parallel.
The pair of ridges found on Greenland's ice sheet appear to have formed long before the recently discovered sets of ridges on Europa formed.
Researchers don't understand why Europa is marked by so many sets of ridges when the moon doesn't have any liquid water on its surface that could have collected and expanded under the icy crust.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'A subject of much speculation, distinctive sets of parallel ridges mark the icy crust of Europa, Jupiter's smallest moon.' |
|
| 'Researchers now claim that the ridges' formation mechanism mirrors that of a strikingly similar pair on Greenland's ice sheet.' |
|
| 'There, surface water seeped through fissures in the sheet and formed a water pocket that subsequently disrupted the overlying ice, forcing fragments of it upward and outward into peaks, as the pocket froze and expanded.' |
|
| 'Although Europa lacks liquid surface water, the same process could be driven by the moon's subsurface ocean.' |
|
Provide Passage Architecture & Core Elements
Main Point: Researchers believe Europa's parallel ridges formed through the same mechanism as similar ridges in Greenland, even though Europa lacks surface water that could be replaced by its subsurface ocean.
Step 2: Interpret the Question Precisely
What's being asked? The main idea of the entire text
What type of answer do we need? A statement that captures the central message of the passage
Any limiting keywords? 'Best states' means we need the most accurate representation
Content Genre: Sciences
Content Format: Text-only
Question Type: Main Point or Purpose (entire)
Language Complexity: Moderate
Step 3: Prethink the Answer
- The main idea should capture that researchers think Europa's ridges formed the same way as Greenland's ridges, despite Europa lacking surface water
- The passage focuses on the similarity in formation process while acknowledging the key difference in conditions
Researchers think that the ridges on Europa and the ridges in Greenland may have been formed by the same process even though Europa, unlike Greenland, doesn't have liquid water on its surface.
- Captures the main research claim about same formation process and includes the key contrast that Europa lacks surface water
- This matches our passage analysis perfectly
The primary difference between the ridges on Europa and the ridges in Greenland is that unlike the Europa ridges, the Greenland ridges are parallel.
- Claims the difference is that Greenland ridges are parallel, but passage says Europa ridges are also parallel
- This misrepresents the actual content
The pair of ridges found on Greenland's ice sheet appear to have formed long before the recently discovered sets of ridges on Europa formed.
- Introduces timing that's nowhere in the passage
- The passage never discusses when either set of ridges formed
Researchers don't understand why Europa is marked by so many sets of ridges when the moon doesn't have any liquid water on its surface that could have collected and expanded under the icy crust.
- Says researchers don't understand why Europa has ridges, but they do have a theory about the subsurface ocean driving the process
- This contradicts the passage's clear explanation