1

Problem

NASA’s Cassini probe has detected an unusual wobble in the rotation of Mimas, Saturn’s smallest moon. Using a computer model to study Mimas’s gravitational interactions with Saturn and tidal forces, geophysicist Alyssa Rhoden and colleagues have proposed that this wobble could be due to a liquid ocean moving beneath the moon’s icy surface. The researchers believe other moons should be examined to see if they too might have oceans hidden beneath their surfaces.

Which choice best states the main idea of the text?

2

Clue

The main idea is often introduced early and reinforced or concluded late. Here, the first sentence states the wobble was detected, and the second sentence gives the proposed explanation (the ocean).

3

Sumup

Please summarize Problem, Hint, Clue

Choices

4

Choice-A

Choice A is incorrect. The text discusses only Mimas and says the researchers proposed (suggested) an ocean, not that they confirmed oceans on several moons.

Wrong Rhoden and colleagues were the first to confirm that several of Saturn’s moons contain hidden oceans.

5

Choice-B

Choice B is incorrect. This contradicts the text. The research did identify a wobble (an "unusual wobble") which is presented as the sign that suggests an ocean.

Wrong Research has failed to identify signs that there is an ocean hidden beneath the surface of Mimas.

6

Choice-C

Choice C is incorrect. The text states they used a computer model to study the wobble in Mimas’s rotation—meaning they did use the rotation analysis. The model was a tool for interpretation, not a replacement for the observation.

Wrong Rhoden and colleagues created a new computer model that identifies moons with hidden oceans without needing to analyze the moons’ rotation.

7

Choice-D

Choice D is correct. This accurately summarizes the entire passage: The wobble (oddity in rotation) was detected, and the researchers' proposal (could be explained) is that it’s caused by a liquid ocean beneath the surface.

Correct "Research has revealed that an oddity in the rotation of Mimas could be explained by an ocean hidden beneath its surface."

8

Answer

Option

D

9

Sumup

Please summarize choices