Logical reasoning PrepTest 129 · Section 1 · Question 21

Incorrect. This is an unbelievably solid trap answer. However, note what the stimulus states the test results showed—most people "had not come into contact" with the bacteria. So it's not that that group ate something infected with the bacteria but were immune to it—it's that they weren't exposed to the bacteria at all. Since that's the case, any immunity people might have is out of scope.

Incorrect. The paradox is that the officials still claim it was the food that made the people sick, so suggesting that it may have been the waiter that was the source of the bacteria doesn't resolve that paradox.

Incorrect. This answer doesn't explain how most of the people eating seafood at the restaurant on that date weren't exposed to the bacteria despite consuming the supposed source of it.

Incorrect. This answer might suggest that there was bacteria at the restaurant, but not the selective nature of the exposure to only some people.

Correct. Argument or Facts:
Facts

Question Type:
Paradox

Stimulus Summary:
Situation - An illness caused by bacteria in seafood was traced to a restaurant on a certain date
Testing - Most people who ate seafood at the restaurant on that date didn't come into contact with the bacteria
Conclusion - The seafood at that restaurant on that date was the cause of the illness

Answer Anticipation:
As with all Paradox questions, we should start with a solid understanding of the paradox itself.

Here, the paradox is that most people who ate seafood at a certain restaurant on a certain date didn't come into contact with the bacteria (though some did), and yet health officials believe that the seafood at that restaurant caused the illness.

While everyone in the stimulus falls into the group of "ate seafood at this restaurant at this date," they can be split into two subgroups—those that got sick and those that didn't and weren't even exposed to the bacteria. Since this stimulus presents a difference between the outcomes these two groups faced, we should look for an answer that brings up a difference between the two groups.

Perhaps the bacteria only affects people who have a preexisting disease, and the group that got sick were the only group with such a disease from among those eating seafood at the restaurant that day. Or perhaps only one type of seafood has the bacteria, and the people who got sick were the only ones to eat it. Anything that explains why this particular group faced a different outcome will serve to resolve this paradox.

Answer Explanation:
This answer explains how most people who ate seafood didn't come into contact with the bacteria, but others did and got sick because of it. If the bacteria contaminated the ingredients of just one seafood dish, then the people who ordered a different dish wouldn't have been exposed to the bacteria, but the people who ordered it would have and would have ended up sick because of it.

Key Takeaway:
It's important to understand—precisely—the paradox in the stimulus. There will be trap answers that get minor details of it wrong ((A)), and answers that provide an explanation for a part of the stimulus but not the paradox ((B) and (D)).