Eight large craters run in a long straight line across a geographical region. Although some of the craters contain ro...

Frank on September 19, 2014

Why choice B is a correct answer itself

I can eliminate other choices however, as to choice B, isn't volcanic event is one of the natural events?

7 Replies

Melody on September 24, 2014

The conclusion of the argument is: the long straight lines "were probably caused by volcanic events rather than meteorites."

Why? We know that 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. Due to the linear quality of the craters, it is unlikely that some of them were caused by volcanoes and others were caused by meteorites.

So, the argument concludes that since the craters are all different ages, they were probably caused by volcanic events rather than by meteorites.

The argument sets up the binary that the lines could have either been caused by meteorites or volcanoes, not both. It then explains that because the craters are all different ages, they were probably caused by volcanic events as opposed to meteorites.

So, how would we strengthen this argument? We should further support the claim that it was, in fact, not meteorites, and instead volcanic activity that caused the eight straight lines of different ages.

Answer choice (B) does just this--"No known natural cause would likely account for eight meteorite craters of different ages forming a straight line."

This answer choice isn't saying that there are no natural causes IN GENERAL that would not account for the eight straight lines, just that there are no known natural causes that would account for eight METEORITE CRATERS of different ages to form straight lines.

Do you see the difference? Answer choice (B) is merely further eliminating the possibility that the meteorites caused the eight lines, since no known natural cause could account for eight meteorite craters of different ages forming a straight line. Therefore, since meteorites could not have caused the lines, they must have been caused by volcanic activity. So, as you can see, answer choice (B) strengthens the argument.

Hope that was helpful! Please let us know if you have any other questions.

on May 23, 2018

How is volcanic activity not a natural cause?

on May 23, 2018

Why is E wrong?

Anita on May 23, 2018

@meisen E would be less able to strengthen the argument because even if there has not been this occurrence before, it still could be possible. Perhaps there was once one with seven in a row? Eight then wouldn't be that far off. B, for the reasons mentioned by @Naz above, is the best answer here.

Ryan on July 27 at 01:19PM

Also notice that E imposes a time restriction, and the craters are all from different times.

Ryan on July 27 at 01:20PM

So just the time factor makes E irrelevant to the passage.

marc on March 25 at 10:33PM

Would A not strengthen the fact that it was likely volcanic activity? I understand providing evidence against one option is a way to decide the answer but would providing further support for the chosen reasoning not suffice?