Io and Europa, the inner two of Jupiter's four largest moons, are

Question

Io and Europa, the inner two of Jupiter's four largest moons, are about the size of Earth's moon and are composed mostly or entirely of rock and metal. Ganymede and Callisto are larger and roughly half ice. Thus, these four moons are somewhat analogous to the planets of the solar system, in which the rock- and metal-rich inner planets are distinct from the much larger gas- and ice-rich outer planets. Jupiter's moons are, however, more "systematic": many of their properties vary continuously with distance from Jupiter. For example, Io is ice-free, Europa has a surface shell of ice, and while Ganymede and Callisto are both ice-rich, outermost Callisto has more.

This compositional gradient has geological parallels. Io is extremely geologically active, Europa seems to be active on a more modest scale, and Ganymede has undergone bouts of activity in its geological past. Only Callisto reveals no geological activity. In similar fashion, Callisto's surface is very heavily cratered from the impact of comets and asteroids; Ganymede, like Earth's moon, is heavily cratered in parts; Europa is very lightly cratered; and no craters have been detected on Io, even though Jupiter's gravity attracts comets and asteroids passing near it, substantially increasing the bombardment rate of the inner moons compared to that of the outer ones. But because of Io's high degree of geological activity, its surface undergoes more-or-less continuous volcanic resurfacing.   1 
 E 
 1. According to the passage, the difference in the amount of cratering on Callisto's and Io's respective surfaces can probably be explained by the difference between these two moons with respect to which of the following factors?

(A) Size
(B) Ice content
(C) The rate of bombardment by comets and asteroids
(D) The influence of Jupiter's other moons
(E) The level of geological activity

2 
 A 
 2. Which of the following best describes the purpose of the second paragraph of the passage?

(A) To provide further evidence of the systematic variation in the characteristics of Jupiter's four largest moons
(B) To present a comprehensive theory to explain the systematic variation in the characteristics of Jupiter's four largest moons
(C) To explain the significance of the systematic variation in the characteristics of Jupiter's four largest moons
(D) To introduce facts that contradict conventional assumptions about Jupiter's four largest moons 
(E) To contrast the characteristics of Jupiter's four largest moons with the characteristics of the planets of the solar system

3 
 A 
 3. The author's reference to Jupiter's gravity in line 25 serves primarily to

(A) indicate why the absence of craters on Io's surface is surprising
(B) explain the presence of craters on the surface of Jupiter's four largest moons
(C) provide an explanation for the lack of geological activity on Callisto
(D) contrast Jupiter's characteristics with the characteristics of its four largest moons
(E) illustrate the similarity between Jupiter's four largest moons and the planets of the solar system

EMPOWERgmatVerbal · Accepted Answer

Io and Europa, the inner two of Jupiter's four largest moons, are about the size of Earth's moon and are composed mostly or entirely of rock and metal. Ganymede and Callisto are larger and roughly half ice. Thus, these four moons are somewhat analogous to the planets of the solar system, in which the rock- and metal-rich inner planets are distinct from the much larger gas- and ice-rich outer planets. Jupiter's moons are, however, more "systematic": many of their properties vary continuously with distance from Jupiter. For example, Io is ice-free, Europa has a surface shell of ice, and while Ganymede and Callisto are both ice-rich, outermost Callisto has more.

This compositional gradient has geological parallels. Io is extremely geologically active, Europa seems to be active on a more modest scale, and Ganymede has undergone bouts of activity in its geological past. Only Callisto reveals no geological activity. In similar fashion, Callisto's surface is very heavily cratered from the impact of comets and asteroids; Ganymede, like Earth's moon, is heavily cratered in parts; Europa is very lightly cratered; and no craters have been detected on Io, even though Jupiter's gravity attracts comets and asteroids passing near it, substantially increasing the bombardment rate of the inner moons compared to that of the outer ones. But because of Io's high degree of geological activity, its surface undergoes more-or-less continuous volcanic resurfacing.

EMPOWER  gmat  Enhanced Explanation:

This passage was retained in the OG 2016.

Paragraph Summary :
 Notes : 1|+| Further -> Icier, resembles solar system, more systematic
 Analysis : The first paragraph is not just a report on the inner moons of Jupiter, but also an argument as to the similarity of Jupiter’s moons to that of the solar system itself. “Thus, these four moons are somewhat analogous to the planets of the solar system” That’s opinion. The rest is evidence supporting that opinion.

Notes : 2|+| Further -> Less geo active
 Analysis : Here, the case is being made that the intensity of geological activity on the surface of the moons varies based on the distance from Jupiter. The further out, the less geologically active, and vice-versa.

OG 2015 #11
OG 2016 #11  
According to the passage, the difference in the amount of cratering on Callisto's and Io's respective surfaces can probably be explained by the difference between these two moons with respect to which of the following factors?
(A) Size
(B) Ice content
(C) The rate of bombardment by comets and asteroids
(D) The influence of Jupiter's other moons
(E) The level of geological activity
 E 
 Detail Question 
Find the Facts: What causes the difference in cratering? Geologic activity. “because of Io's high degree of geological activity, its surface undergoes more-or-less continuous volcanic resurfacing” so the closer to Jupiter, the more active the volcanic activity, and the volcanoes essentially erase the craters off the surface more frequently, the closer the moon is to Jupiter. Which option says that? E. It’s not about the size, the ice content ,or the influence of Jupiter’s other moons. Those are the 3 easy outs. Option C is the runner up. We know it’s not C because the rate of bombardment intensifies the closer the moon is to Jupiter, but the closer the moon is to Jupiter, the fewer craters, so it can’t be about the bombardment. Again, at the end of paragraph 2, we’re told that the volcanic activity is what wipes the surface.

OG 2015 #12
OG 2016 #12  
Which of the following best describes the purpose of the second paragraph of the passage?
(A) To provide further evidence of the systematic variation in the characteristics of Jupiter's four largest moons
(B) To present a comprehensive theory to explain the systematic variation in the characteristics of Jupiter's four largest moons
(C) To explain the significance of the systematic variation in the characteristics of Jupiter's four largest moons
(D) To introduce facts that contradict conventional assumptions about Jupiter's four largest moons 
(E) To contrast the characteristics of Jupiter's four largest moons with the characteristics of the planets of the solar system
 A 
 Purpose Question 
What’s The Purpose of Paragraph 2? Further proof of systematic relationship of the moons. The further the moon, the greater the catering. That is proof of a system in which the distance from Jupiter impacts the character of the moons. Which option says that? A) To provide further evidence of the systematic variation in the characteristics of Jupiter's four largest moons
B) Easy Out #1 Is this passage, let alone paragraph 2 actually presenting a COMPREHENSIVE theory? No. How would we know this is a comprehensive treatment. This option has the right flavor, but warps it by making it too extreme.
C) The runner up. Does this passage actually provide information as to how significant this systematic relationship is? No Just because the author is describing the systematic relationship doesn’t automatically make that issue a significant one. That distorts, or in other words warps what the answer should say.
D) Easy Out #2 Left field. Nothing in the passage indicates that these facts used to support this systematic theory counter the conventional thinking. For all we know, this passage might actually reinforce conventional assumptions, and beliefs about the moons.
E) Easy Out #3 Even though there is reference to the similarity of Jupiter’s moons to the planets in the solar system, that’s not automatically the goal if either paragraph. Instead, the author is really just drawing on the familiarity of the solar system to help illustrate what’s going on with Jupiter’s moons.

OG 2015 #13
OG 2016 #13  
The author's reference to Jupiter's gravity in line 25 serves primarily to
(A) indicate why the absence of craters on Io's surface is surprising
(B) explain the presence of craters on the surface of Jupiter's four largest moons
(C) provide an explanation for the lack of geological activity on Callisto
(D) contrast Jupiter's characteristics with the characteristics of its four largest moons
(E) illustrate the similarity between Jupiter's four largest moons and the planets of the solar system
 A 
 Purpose Question 
What’s the purpose of the reference to gravity in line 25? The passage points out that we’d expect more craters the closer we got to jupiter because of Jupiter’s gravity, but instead we see fewer craters. That seeming paradox is the point. Which option expresses that idea?
A) Yes! To point out that the absence of craters is not what we’d expect
B) A 180. We know for a fact that not all of the 4 moons have craters. Io is extremely volcanic, and the passage says that “its surface undergoes more-or-less continuous volcanic resurfacing.”
C) Is the entire purpose of the mention of Jupiter’s gravity to talk about the lack of activity on Callisto? No In fact Callisto is month the furthest out.
D) Easy Out #2 Is the purpose of sharing the information in paragraph 2 to contrast Jupiter’s characteristics to that of it’s moon? no. 
E) Even though the passage does reference the similarity in P1, is that the purpose of referencing Jupiter’s gravity here? No. The reason why the author is referencing Jupiter’s gravity is to point out why it’s surprising these innermost moons don’t have more craters since they’re more likely to be bombarded.

GMATNinja · Answer

The author uses the word "systematic" to describe Jupiter's moons as following a regular pattern (i.e., arranged in an ordered fashion). Ice content and geological activity are two properties of the moons that "vary continuously with distance from Jupiter"; thus, those two properties follow a regular, ordered pattern. In contrast, say another planet has 5 moons, A through E, where A is closest to the planet and E is the farthest away from the planet. If A has a little bit of ice, B has no ice, C has the same amount of ice as A, D has much more ice than A and C, and E has the same amount as E (so B < A=C < D=E), we might be able to say that the ice content  generally  increases as we get farther away from the planet, but the ice content does not vary continuously with distance. This would be a less regular pattern than that of Jupiter's moons, and we could describe Jupiter's moons as being more "systematic" than the moons of our made-up planet.
 
Question #12 does not ask about the primary purpose  of the passage . Instead, it asks about "the purpose  of the second paragraph  of the passage". In paragraph one, the author describes Jupiter's moons as more systematic than the planets of the solar system. The author then uses ice content as an example to support that statement.

In paragraph two, the author describes two other examples to support the statement that Jupiter's moons are more systematic than the planets of the solar system (geological activity and cratering). Thus, paragraph two provides "further evidence of the systematic variation in the characteristics of Jupiter's four largest moons", making (A) the correct choice.

Choice (B) is well beyond the scope of paragraph two, which only provides two examples of characteristics of Jupiter's four largest moons that vary systematically. While paragraph two does explain why cratering varies with distance, it does not explain  why  geological activity varies with distance (or  why  ice content varies with distance). Paragraph two certainly does not "present a  comprehensive theory to explain  the systematic variation in the characteristics of Jupiter's four largest moons."

As for choice (C), the author does explain how geological activity affects the surface features of the moons, but the author does not "explain the significance of the systematic variation in the characteristics of Jupiter's four largest moons". Why is it significant that Jupiter's moons are more systematic than the planets of the solar system? In other words,  why  does it matter that "many of their properties vary continuously with distance from Jupiter?" The author describes those characteristics but does not describe why their systematic variations are significant. Choice (C) is beyond the scope of the passage and certainly beyond the scope of paragraph two.

SOURH7WK · Answer

In 5:47 min, My Answers EAA. 
1st Question: refer line 19
Only 2nd question bothered me. The contenders were A & B. The word theory in option B is not correct and I think author was providing evidences rather than any theory.
3rd: Line 23-30. Author was explaining a surprising fact. For this type of Q: Once u comprehend the passage portion, cover up the answer choices and try to answer from ur comprehension and then try to eliminate the answer choices. It works best.

bablu1234 · Answer

OG 2015 #13
OG 2016 #13  
The author's reference to Jupiter's gravity in line 25 serves primarily to
(A) indicate why the absence of craters on Io's surface is surprising
(B) explain the presence of craters on the surface of Jupiter's four largest moons
(C) provide an explanation for the lack of geological activity on Callisto
(D) contrast Jupiter's characteristics with the characteristics of its four largest moons
(E) illustrate the similarity between Jupiter's four largest moons and the planets of the solar system
 A 
 Purpose Question 
What’s the purpose of the reference to gravity in line 25? The passage points out that we’d expect more craters the closer we got to jupiter because of Jupiter’s gravity, but instead we see fewer craters. That seeming paradox is the point. Which option expresses that idea?
A) Yes! To point out that the absence of craters is not what we’d expect
B) A 180. We know for a fact that not all of the 4 moons have craters. Io is extremely volcanic, and the passage says that “its surface undergoes more-or-less continuous volcanic resurfacing.”
C) Is the entire purpose of the mention of Jupiter’s gravity to talk about the lack of activity on Callisto? No In fact Callisto is month the furthest out.
D) Easy Out #2 Is the purpose of sharing the information in paragraph 2 to contrast Jupiter’s characteristics to that of it’s moon? no. 
E) Even though the passage does reference the similarity in P1, is that the purpose of referencing Jupiter’s gravity here? No. The reason why the author is referencing Jupiter’s gravity is to point out why it’s surprising these innermost moons don’t have more craters since they’re more likely to be bombarded.

In Q13, in OG line nums are confusing. The reference to gravity on line 25 doesn't provide any surprise of why craters are low in numbers on Io. The surprising fact is on line 30. So reference to gravity should have been because of B and not A. Though I have to respect official answer but OG should have omitted reference to line num 25 in their question stem 13. Without referring to line num 25, A makes sense.

NaeemHasan · Answer

How will I understand that "  volcanoes essentially erase the craters off the surface more frequently, the closer the moon is to Jupiter " as I have no knowledge about it?

EMPOWERgmatVerbal · Answer

Hi NaeemHasan,

I'd be happy to help. You don't need subject specific knowledge to dissect the meaning of this description.

Let me ask you to take your best take on what you think it means, right or wrong? Try to take it apart piece by piece. I'll provide some guidance thereafter.

EMPOWERgmatVerbal · Answer

Hi NaeemHasan,

I think you may have misunderstood what I was asking you. Can you make an attempt to share your best understanding of what "volcanoes essentially erase the craters off the surface more frequently, the closer the moon is to Jupiter" means?

I'll help you from there, but I'd like to see where your understanding lies now first.

EMPOWERgmatVerbal · Answer

Hi NaeemHasan,

Well done! You ABSOLUTELY got it.

The moral of the story is: don't be intimidated by unfamiliar vocab. Gain comfort in the underlying concept. That's a skill you'll be drawing on extensively in B-school, and in the meantime, it's a skill that will help you boost your GMAT Verbal score to help you gain admission.

adkikani · Answer

Hi Gmatninja, Gmatninja2
Can you explain what is systematic about Jupiter's moons from passage.
From para 1 it talks about ice composition in moons and second para talks about
crates (ie uneven surfaces formed due to impact of comets/asteroids) Through out the passage there are two co-relationships (distance and ice) a (crates and re-surfing of surface of Io due to impact of volcanoes) but how does it make Jupiter's moon systematic? Further more, since earlier sentence talked about its analogy with planet w.r.t material composition what do I infer from : J's moons are systematic
Also I am confused about options B and C regarding primary purpose of passage.
(B) To present a comprehensive theory to explain the systematic variation in the characteristics of Jupiter's four largest moons
Well author does present a theory to explain coverage of ice and less occurrence of craters in Jupiter's planets. Why is this option incorrect?
(C) To explain the significance of the systematic variation in the characteristics of Jupiter's four largest moons
Author does mention how change in surface due to volcanic eruption led to even surface of Io. Why is this option incorrect?
I completely am foxed that OA is A, can you explain on which grounds (A) makes proper sense?
WR,
Arpit

mr.adsingh · Answer

finished in 2:49, 0:44, 1:06 ~ 4.5mins = C(got wrong - A is right here),A,A
got one mistake!

I am struggling to get all the right answers in any passage.
Never got all right, do not know how to improve.

any suggestions will be helpful

Thanks,
AD

aragonn · Answer

P1 - J's 4 moons are defined, with their properties.
P2 - geological activities of J's moons' are defined.

1. According to the passage, the difference in the amount of crate ring on Callisto's and Io's respective surfaces can probably be explained by the difference between these two moons with respect to which of the following factors? - P2
Lines to look for - Only Callisto reveals no geological activity. Callisto's surface is very heavily cratered from the impact of comets and asteroids; no craters have been detected on Io, even though Jupiter's gravity attracts comets and asteroids passing near it,Io is extremely geologically active
(A) Size - No
(B) Ice content - no
(C) The rate of bombardment by comets and asteroids --- comets and asteroids only happens on Callisto but no geological activity. No crate on IO. this one is not a factor on Io.
(D) The influence of Jupiter's other moons --- No 
(E) The level of geological activity --- yes
----------------------------------

2. Which of the following best describes the purpose of the second paragraph of the passage?
refer P2 ; frankly speaking, I think A,B, C are very close. Let see the difference in words. 
(A) To provide further evidence of the systematic variation in the characteristics of Jupiter's four largest moons --- P1 provided some difference b/w the moons. P2 take that to next level . This seems the best option. 
(B) To present a comprehensive theory to explain the systematic variation in the characteristics of Jupiter's four largest moons --- comprehensive theory .... there is no defined theory here. 
(C) To explain the significance of the systematic variation in the characteristics of Jupiter's four largest moons --- yes author is describing a systematic relationship or say difference in characteristics but is it explaining the significance of it. I think A is better option then this one. though it is close.
(D) To introduce facts that contradict conventional assumptions about Jupiter's four largest moons ---- contradict conventional assumptions - no such thing
(E) To contrast the characteristics of Jupiter's four largest moons with the characteristics of the planets of the solar system --- No contrast is defined.
-----------------------------------

3. The author's reference to Jupiter's gravity in line 25 serves primarily to

lines to look for - no craters have been detected on Io, even though Jupiter's gravity attracts comets and asteroids passing near it, substantially increasing the bombardment rate of the inner moons compared to that of the outer ones. Straight A is the answer.

(A) indicate why the absence of craters on Io's surface is surprising

adsingh · Answer

I have a doubt in OA 1 of the passage.

Crating is created by the impact of outside heavenly bodies, which impact the surface of a planet. How can an internal activity, geology, be responsible for creating craters. And even the passage doesn't suggest that.

homersimpsons · Answer

Q1. According to the passage, the difference in the amount of cratering on Callisto’s and Io’s respectivesurfaces can probably be explained by the difference between these two moons with respect to which of the following factors?
A. Size
B. Ice content
C. The rate of bombardment by comets and asteroids
D. The influence of Jupiter’s other moons
E. The level of geological activity
 Supporting idea 
Cratering is discussed in the second paragraph. The passage states that Callisto is heavily cratered, while Io has no detectable craters. Io is the moon closest to Jupiter, and Callisto is the farthest away. Their relative positions are accompanied by a corresponding difference in geological activity: Io is very geologically active, while Callisto is not active at all. Io’s geological activity means that it is being regularly resurfaced, so it is unlikely to retain any evidence of cratering—unlike Callisto, which experiences no resurfacing, leaving its craters intact.
A. While the passage makes clear that Callisto is larger than Io, it does not address whether their relative size explains the difference in their respective amounts of cratering.
B. According to the passage, Callisto and Io differ in terms of their ice content, but nothing in the passage indicates that that content affects the cratering on their surfaces.
C. The passage states that Io experiences a higher rate of bombardment than Callisto does, but while that bombardment most likely causes cratering on Io, its surface does not retain those craters. Thus, the rate of bombardment does not, in itself, explain the difference in cratering on the surface of thetwo moons.
D. The only other moons of Jupiter discussed in the passage are Ganymede and Europa, and the passage does not consider their effect on the cratering of Callisto and Io.
E. E  Correct.  Because Io experiences a high degree of geological activity, its surface is continuously resurfaced, which means that the surface shows no craters. Callisto, on the other hand, is not geologically active and thus is not resurfaced regularly, which explains why its surface is heavily cratered.
 The correct answer is E.

Q2. Which of the following best describes the purpose of the second paragraph of the passage?
A. To provide further evidence of the systematic variation in the characteristics of Jupiter’s four largest moons
B. To present a comprehensive theory to explain the systematic variation in the characteristics of Jupiter’s four largest moons
C. To explain the significance of the systematic variation in the characteristics of Jupiter’s four largest moons
D. To introduce facts that contradict conventional assumptions about Jupiter’s four largest moons
E. To contrast the characteristics of Jupiter’s four largest moons with the characteristics of the planets of the solar system
 Evaluation 
This question depends on understanding how the second paragraph functions in the context of the passage as a whole. The first paragraph discusses the way in which the composition of Jupiter’s four largest moons varies with distance from Jupiter, and the second paragraph extends the idea of distance-based variation to geological activity and surface appearance.
A.  Correct . The second paragraph presents evidence related to the amount of geological activity andsurface cratering in order to extend the first paragraph’s suggestion that the characteristics of Jupiter’s four largest moons vary systematically based on their distance from Jupiter.
B. The passage does not offer a theory to account for the systematic variation in the characteristics of Jupiter’s largest moons; it merely describes several instances of that variation.
C. The second paragraph provides more examples of the systematic variation in the characteristics of Jupiter’s largest moons rather than explaining that variation’s significance.
D. The passage describes Jupiter’s moons but does not identify any conventional assumptions about those moons that are contradicted by facts introduced in the passage.
E. The first paragraph suggests that Jupiter’s moons exhibit differences in characteristics that are more “systematic” than are those of the planets in the solar system, but the characteristics are not themselves contrasted; in fact, the first paragraph suggests that they are similar. The second paragraph does not discuss the planets of the solar system at all.
 The correct answer is A.

Q3. The author’s reference to Jupiter’s gravity in line 25 serves primarily to
A. indicate why the absence of craters on Io’s surface is surprising
B. explain the presence of craters on the surface of Jupiter’s four largest moons
C. provide an explanation for the lack of geological activity on Callisto
D. contrast Jupiter’s characteristics with the characteristics of its four largest moons
E. illustrate the similarity between Jupiter’s four largest moons and the planets of the solar system
 Evaluation 
The reference to Jupiter’s gravity is part of the author’s discussion of cratering on Jupiter’s moons; Jupiter’s gravity is strong enough to attract comets and asteroids that then bombard its inner moons. A high bombardment rate would seem to indicate that a great deal of cratering would occur on those inner moons, and yet the passage reports that, unexpectedly, on the innermost moon, Io, no craters have been detected.
A.  Correct . Jupiter’s gravity attracts comets and asteroids, which increases the bombardment rate of its inner moons, including Io. This bombardment makes it surprising that Io’s surface shows no cratering.
B. The passage discusses the likely effect of Jupiter’s gravity on its inner moons but not its outer moons; two of the large moons the passage discusses are outer moons.
C. According to the passage, Callisto, an outer moon, lacks geological activity because of its distance from Jupiter; Jupiter’s gravity is not offered as a contributing factor to this inactivity.
D. The passage does not contrast Jupiter with its moons; rather, it compares the moons to one another.
E. The first paragraph of the passage suggests that Jupiter’s moons vary in a way similar to that of the planets of the solar system, but the author does not refer to Jupiter’s gravity to illustrate the similarity in this variation.
 The correct answer is A.

Meet95 · Answer

ques 2
A. hold
B. hold
C. hold
D .contadict .nothing like that.eliminate
E . contrast.nothing like that-eliminate

so option A,B,C.
in B- it is written a theory .no word related to theory has been used also by reading it sound like a fact or evidence.eliminate B.
C- what significance is theory is causing .i dont think gelogical activities or structure have any significance as discussesd in the passage-elimnate C

kntombat · Answer

Sajjad1994 , if possible can the format of the questions be adjusted. 
The words are on top but the options are down.

skhanna10 · Answer

For question 2, option C, I do believe that the significance of the relationship is explored

The fact that there is a difference in geological activity that causes less craters in the inner moons, despite the higher influence of gravity, indeed explains the significance of the relationship. I am not able to eliminate option C.

GMATNinja · Answer

Check out our earlier analysis of why answer choice (C) is wrong  here , and let us know if that clears things up!

pulkitrana · Answer

Q1. According to the passage, the difference in the amount of cratering on Callisto’s and Io’s respectivesurfaces can probably be explained by the difference between these two moons with respect to which of the following factors?
A. Size
B. Ice content
C. The rate of bombardment by comets and asteroids
D. The influence of Jupiter’s other moons
E. The level of geological activity
 Supporting idea 
Cratering is discussed in the second paragraph. The passage states that Callisto is heavily cratered, while Io has no detectable craters. Io is the moon closest to Jupiter, and Callisto is the farthest away. Their relative positions are accompanied by a corresponding difference in geological activity: Io is very geologically active, while Callisto is not active at all. Io’s geological activity means that it is being regularly resurfaced, so it is unlikely to retain any evidence of cratering—unlike Callisto, which experiences no resurfacing, leaving its craters intact.
A. While the passage makes clear that Callisto is larger than Io, it does not address whether their relative size explains the difference in their respective amounts of cratering.
B. According to the passage, Callisto and Io differ in terms of their ice content, but nothing in the passage indicates that that content affects the cratering on their surfaces.
C. The passage states that Io experiences a higher rate of bombardment than Callisto does, but while that bombardment most likely causes cratering on Io, its surface does not retain those craters. Thus, the rate of bombardment does not, in itself, explain the difference in cratering on the surface of thetwo moons.
D. The only other moons of Jupiter discussed in the passage are Ganymede and Europa, and the passage does not consider their effect on the cratering of Callisto and Io.
E. E  Correct.  Because Io experiences a high degree of geological activity, its surface is continuously resurfaced, which means that the surface shows no craters. Callisto, on the other hand, is not geologically active and thus is not resurfaced regularly, which explains why its surface is heavily cratered.
 The correct answer is E.

Thanks, your explanation of Question 1 was of great help.

GMATCoachBen · Answer

Bunuel

There is a typo in question 1; it should say "cratering" instead of "crate ring"

Thanks!

Io and Europa, the inner two of Jupiter's four largest moons, are

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Io and Europa, the inner two of Jupiter's four largest moons, are

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