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Complete Question Explanation

The correct answer choice is (B).

Answer choice (A):

Answer choice (B): This is the correct answer choice.

Answer choice (C):

Answer choice (D):

Answer choice (E):

This explanation is still in progress. Please post any questions below!
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I was wondering if someone could help me with the thought process for this question. The question is directed towards the last paragraph of the excerpt and is asking to cast the most doubt on the theory provided. The last paragraph is a bit long, so when completing this section under the time constraints, I looked at the first sentence which essentially sets up what the paragraph is going to talk about. The first sentence says that the volcanic-eruption theory accounts for iridium deposits, similar to that of the other theory and actually explains things that the impact theory has either left out or was unable to explain. I assumed this part of the sentence was referring to the drop in sea level and the extinction of marine organisms. My thinking on this would be the correct answer would be attacking one of these. When doing this section under timed-conditions, I picked E. To be honest, I think it was a hasty/not well thought out choice. I think I was just drawn to the part about marine species and didnt think about what it was actually saying. However, I am not sure I quite understand why B is the correct answer. This answer seems, at least to me, directed at lines 21-25. Could someone explain why B applies? Thank you.
 Adam Tyson
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Sure thing, asuper! All of the theories described In this passage are about the cause of the extinction of the dinosaurs. It's one giant causal argument! To weaken any causal argument, one might suggest an alternate cause, or show the cause occurring and the effect not occurring, or the effect occurring at a time when the cause does not, or showing that the purported cause and effect could be reversed, or showing that there might be a problem with the data that was used to support the causal claim.

Answer B is telling us that the cause, volcanic eruption, has occurred many times without the corresponding effect, extinctions, also occurring. That's a classic way to weaken a causal argument, and it's what makes answer B the best answer of the bunch here.

Answer E is a trap. Just because marine species are more vulnerable to sudden changes than gradual changes doesn't mean a gradual change couldn't be the cause of their extinction. I'm more vulnerable to indigestion when I eat jalapenos than when I eat tomatoes, but tomatoes could still upset my tummy!

Use those five casual attacks to weaken any casual argument, whether in RC or in LR, and you'll be well on the way to mastering causality as it's used in the LSAT. Good luck, keep pounding!

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