Few, if any, carbonated beverages contain calcium. Some very popular ones, however, contain significant amounts of ca...

shunhe on July 7, 2020

Hi @ElizabethGlassmann,

Thanks for the question! So let’s recap the argument real quickly. We’re told that few carbonated beverages contain calcium, but some very popular ones have a lot of caffeine, which makes people excrete more calcium than normal. And teenagers who drink more carbonated beverages with caffeine more often have broken bones than those who don’t drink that many carbonated beverages. Finally, we’re told that calcium deficiency can make bones more brittle, and the argument then concludes that teens who drink more carbonated beverages have more broken bones because of the caffeine consumption.

So now we’re looking for something that can weaken the argument. And there are a lot of ways we could do that, such as by introducing alternative explanations (something else in the carbonated beverages, or something that differentiates teens who drink carbonated beverages as a class). Now take a look at (A). It tells us that teens who drink lots of carbonated beverages with caffeine drink less calcium-rich beverages than others. Well, we know that less calcium can make bones more brittle. So if (A) is true, then there’s another possibility for why these teens have more broken bones: not because of the caffeine, but because they don’t intake as much calcium! That weakens the conclusion that the caffeine’s to blame, and so (A) definitely weakens.

(B), on the other hand, is completely irrelevant. We’re comparing teens who drink more carbonated beverages to teens who don’t drink as much, not older people and younger people. So (B) gets the groups wrong and doesn’t affect the stimulus at all.

(C) also doesn’t really weaken the argument. Remember that “some” on the LSAT means “at least one.” So let’s say (C) is true, and there’s at least one (possibly even exactly one) teenager who has a calcium deficiency without drinking caffeine doesn’t mean that overall, it’s not true that people who drink caffeine will have weaker bones. That person (or those people) could just be an outlier, so (A) definitely weakens more than (C), and (C) can be ruled out.

Hope this helps! Feel free to ask any other questions that you might have.