Situation: Eight large craters, but some of different ages run in a long straight line. Although some of the craters contain rocks that have undergone high-pressure shocks characteristic of meteorites slamming into Earth, these shocks could also have been caused by extreme volcanic events.

Conclusion: Craters were probably caused by volcanic events rather than meteorites since the craters are all different ages.

Objective: To find any option the increases the belief that volcanic activity formed the craters.

(A) A similar but shorter line of craters that are all the same age is known to have been caused by volcanic activity.-Incorrect. We are not interested in craters that are all of same age.

(B) No known natural causes would likely account for eight meteorite craters of different ages forming a straight line.-Correct. The option clearly states that there is no known cause for meteorite craters of different ages forming a straight line, strengthening the conclusion that volcanic activity must be the cause.

(C) There is no independent evidence of either meteorites or volcanic activity in the region where the craters are located.-Incorrect. This weakens the conclusion.

(D) There is no independent evidence of a volcanic event strong enough to have created the high-pressure shocks that are characteristic of meteorites slamming into Earth.-Incorrect. This weakens the conclusion.

(E) No known single meteor shower has created exactly eight impact craters that form a straight line.-Incorrect. Just because no known single meteor shower has created exactly eight impact craters that form a straight line, it doesn't mean it will never happen. This doesn't strengthens the conclusion.

Clear B.Other options are not even close.

Some mild argument can be made for E.But meteorite showers are not the same as meteorite.

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Passage Analysis

Eight large craters run in a long straight line across a geographical region.
Eight huge pits formed out of some huge impact are present along a straight line in a particular region of the earth

Although some of the craters contain rocks that have undergone high-pressure shocks characteristic of meteorites slamming into Earth,
One or more of these craters contain rocks whose properties point to a reason of origin as meteorite impact.Still...

these shocks could also have been caused by extreme volcanic events.
It is also possible that extreme volcanic eruptions led to these formations as well.

Because of the linearity of the craters, it is very unlikely that some of them were caused by meteorites.
The chance that one or more of the craters are formed by meteorite impact is extremely low considering that they are placed in an exact straight line.

Thus, since the craters are all different ages,
Also, considering that these craters were formed in different time periods,

they were probably caused by volcanic events rather than meteorites.
The author concludes that the actual reason of formation of this geographical feature are volcanos, not meteorites.

Question Stem: Which one of the following statements, if true, would most strengthen the argument?
Direct strengthener question

Thought process

The strengthener framework should ask
What new information will make us believe more in the conclusion that the line of craters was formed by volcanos and not meteorites
Given that
they are placed in a straight line but were formed in different ages.

Possible strengtheners:
Any information that tells us that volcanic eruptions can happen along a straight line.
Any information that tells us so many meteorite craters forming a line is extremely unlikely.
Any information that denies a combination of meteors and volcanoes together leading to the formation.

Option Analysis

(A) A similar but shorter line of craters that are all the same age is known to have been caused by volcanic activity
Craters formed during the same period are not similar to the case in hand. Hence this option is irrelevant.

(B) No known natural causes would likely account for eight meteorite craters of different ages forming a straight lineThis option increases our belief in the conclusion that meteorites did not lead to the crater line. This is in line with the second type of strengthener mentioned. Hence a correct answer

(C) There is no independent evidence of either meteorites or volcanic activity in the region where the craters are located
Denies the cause we want to support as well. Cannot be the correct answer.
(D) There is no independent evidence of a volcanic event strong enough to have created the high-pressure shocks that are characteristic of meteorites slamming into Earth
Against the hypothesis supported by the conclusion. Hence not a strengthener.

(E) No known single meteor shower has created exactly eight impact craters that form a straight line
Not relevant because, like option A, it talks about only craters formed during the same time period.

Answer is B.
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Thansk for the explanation, but isn't volcanic eruption a natural cause.
In B if meteorites are ruled out so the volcanic eruptions may also be ruled out.

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aish5063
The trick there is that B refers to the craters as meteorite craters. So it's not saying that no natural causes could be at work--that would support an argument about human activity or aliens. Rather, it's saying that nothing in nature could have made the meteorites fall in that linear pattern. Basically, it's strengthening the link between a premise (linear pattern) and an intermediate conclusion (unlikely to have been meteorites).
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Hi experts,

Is it a fair thought to discard E because it talks about “exactly 8..” and the argument poses the possibility for “some..that could have been...”

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UsamaGuddar
That's right--the meteorite explanation doesn't require one big event. In fact, the author has stated that the craters are all from different times, so E is puncturing an argument that no one is making.
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How is it B?
"No known natural causes". It's not clear what 'natural clauses' means, but I think I can use common sense and infer that volcanic events are one such natural cause. E seams to weaken not strengthen? The vocab on this threw me off...
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