LSAT Explanation PT 35, S1, Q16: On the basis of the available
LSAT Question Stem
Which one of the following is the main conclusion of the argument?
Logical Reasoning Question Type
This is a Main Conclusion question.
Correct Answer
The correct answer to this question is C.
LSAT Question Complete Explanation
This LSAT problem is a Main Conclusion question, which asks us to identify the main conclusion of the argument presented in the passage. The passage presents evidence that challenges the prevailing view that Antarctica has been covered by ice for at least the past 14 million years. The author's main conclusion can be found in the third sentence of the passage, which is indicated by the conclusion marker "therefore." Now, let's analyze each answer choice in detail.
Answer choice (A): This choice is incorrect because, although the author presents evidence that challenges the prevailing view, we don't know if the general view has changed accordingly. The author's viewpoint is in conflict with the prevailing view about Antarctica.
Answer choice (B): This choice is incorrect and can be quickly eliminated. If the ancient fossils found in Antarctica can also be found in places other than ocean-floor sediments, the author's conclusion would be weakened. The main issue is whether Antarctica has been continuously covered by ice, not the location of the fossils.
Answer choice (C): This is the correct answer choice. It paraphrases the author's main conclusion found in the third sentence of the passage, which states that the ice sheet covering Antarctica has not been continuously present throughout the past 14 million years.
Answer choice (D): This choice is incorrect because the main point of the argument is whether Antarctica was submerged, not why it was submerged. The last sentence of the passage, which mentions the possible causes of the melting ice sheet, is a premise rather than the conclusion. The phrase "after all" indicates a premise, not a conclusion.
Answer choice (E): This choice is incorrect because it is a premise explaining why the author believes Antarctica was not continuously covered by ice, rather than the main conclusion. Test makers often place the conclusion somewhere in the middle of the passage, and in this case, the last sentence is not the conclusion. The phrase "after all" indicates a premise, not a conclusion.