December 2010 LSAT Section 2 Question 3

What is the author's primary purpose in referring to the rate of growth of a North American lichen species (lines 29-...

caydencemarley on September 17, 2020

Why is answer choice A incorrect?

I can see why E is correct, but I am having a difficult time distinguishing the significant difference between these two choices. I can only seem to reason that because lichens grow "at 9.5 millimetres per century" that answer A, in discussing growth on newly exposed rock, would be irrelevent since we cannot determine if lichen growth over a century counts as growing on "newly exposed rock". Am I correct in reasoning this or no? Thank you for any help!

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Emil-Kunkin on June 30 at 10:19PM

The author is trying to give an example of one of the growth rates of lichens in order to show how lichens can establish the age at which a surface was exposed. I think you're right it's not related to the idea that we're trying to show if the growth is fast or slow, what we care about is that we can determine the age.