LSAT 132 | Section 1 | Reading Comprehension: Q20

RC Question 20 Explanation

DISCUSSION: The right answer is a little tricky to justify. You have to use common sense. This is a misunderstood issue on the LSAT. A lot of people think you can’t use outside knowledge.

But outside knowledge is allowed, even encouraged. You just have to use it in the right way. You can only assume things that no one would disagree with. You’re supposed to assume the knowledge of a well informed person. For example, someone who knows about tubers knows they’re carbs. Since this is true in real life, it’s a fact you can use.

What you can’t use as outside knowledge are opinions that people might disagree with, such as “taxes are good/bad”.

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1. The passages never explicitly mention wild carbohydrates, so there is no comparison.
2. Assuming acorn flour is a carbohydrate, passage A contradicts this answer. See line 27. Passage B never mentions processed carbohydrates.
3. CORRECT. Passage B says this directly. See lines 66-68.
   Passage A is a bit less supported. You have to read between the lines. There are two lines that support this. First, lines 8-10 say that carbohydrates’ texture and composition affect caries. This likely means: “Carbohydrates have different textures. Carbohydrate texture tends to promote caries, but some textures do this more than others.” After all, you know from common knowledge that carb textures differ.
    
   Second, line 31 says that tubers are a highly cariogenic wild food. Again, it’s common knowledge that tubers are carbohydrates. No well informed person would disagree with this. Lines 29-31 say that wild plants “included several cariogenic foods”. This implies that some wild foods (plants) are not cariogenic. An it is common knowledge that most wild plants are carbs. So some carbs are not cariogenic.
4. Only passage B mentioned fiber.
5. Neither passage says that carbohydrates change if they’re cultivated.