LSAT Question Explanation
PT 108, Section 3, Question 21
WeakenArgument structure
At least 50 million people in North America should take lactase supplements.
The lactase enzyme helps people digest dairy products. People drank a liter of milk on an empty stomach for an experiment, and many of them then had digestive issues because of a lack of lactase.
Explanation
This is not a very good argument. Where is the 50 million number coming from? The author never indicates that the proportion who had issues in the study would extrapolate to 50 million North Americans. Based on what we know about the study the number of people who should take lactase supplements could be way lower than that.
The way the study was conducted was also problematic. Drinking a liter of milk on an empty stomach doesn't seem like normal behavior, and could have much more adverse effects on the digestive system than dairy consumption in conjunction with other foods. Or other dairy products besides milk could be less harmful. We don't know if the consumption in the study actually reflects people's real life behavior.
Lastly, it's possible that many people who are lactose intolerant just avoid dairy in general. If that's the case then they wouldn't need lactase supplements at all.
Answer choices
This would strengthen the argument by showing that if the subjects had consumed milk not on an empty stomach their digestive issues may have been even worse.
This would weaken. It points out that the study referenced in the argument may be somewhat ridiculous and doesn't really indicate whether most of the subjects would need a lactase supplement in real life.
This doesn't affect the argument. We don't know how old the subjects were, or how old most North Americans are, etc. Maybe young people need the supplement more than old, but that doesn't weaken the conclusion.
If anything I think this could slightly strengthen by showing the importance of combating lactose intolerance.
Similar to (A) this would strengthen by showing that other forms of dairy besides milk have even more adverse effects on the digestive system.