LSAT Explanation PT 29, S1, Q10: The symptoms of hepatitis A appear

LSAT Question Stem

Which one of the following, if true, most helps resolve the apparent discrepancy in the information above? 

Logical Reasoning Question Type

This is a Paradox question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

First, let's analyze the passage and summarize any unclear or confusing parts. The passage tells us that the symptoms of hepatitis A appear no earlier than 60 days after a person has been infected. In a test of a hepatitis A vaccine, 50 people received the vaccine and 50 people received a harmless placebo. Although some people from each group eventually exhibited symptoms of hepatitis A, the vaccine as used in the test is completely effective in preventing infection with the hepatitis A virus.

The apparent discrepancy in the passage is that some people who received the vaccine still exhibited symptoms of hepatitis A, even though the vaccine is said to be completely effective in preventing infection with the hepatitis A virus.

Now, let's analyze the question type and what it's asking us to do. This is a Paradox question, which asks us to resolve the apparent discrepancy in the information above.

Let's go through each answer choice in detail:

a) The placebo did not produce any side effects that resembled any of the symptoms of hepatitis A.

This answer choice doesn't help to resolve the discrepancy because it only tells us about the placebo group. It doesn't provide any information about the vaccinated group, which is where the discrepancy lies.

b) More members of the group that had received the placebo recognized their symptoms as symptoms of hepatitis A than did members of the group that had received the vaccine.

This answer choice also doesn't help to resolve the discrepancy because it focuses on the recognition of symptoms rather than the effectiveness of the vaccine in preventing infection.

c) The people who received the placebo were in better overall physical condition than were the people who received the vaccine.

This answer choice is not helpful because it compares the physical condition of the placebo group to the vaccinated group, which doesn't address the discrepancy regarding the vaccine's effectiveness in preventing infection.

d) The vaccinated people who exhibited symptoms of hepatitis A were infected with the hepatitis A virus before being vaccinated.

This answer choice resolves the discrepancy by explaining that the people who exhibited symptoms of hepatitis A after receiving the vaccine were already infected before being vaccinated. This means that the vaccine is still completely effective in preventing new infections, as the passage states.

e) Of the people who developed symptoms of hepatitis A, those who received the vaccine recovered more quickly, on average, than those who did not.

This answer choice doesn't help to resolve the discrepancy because it focuses on the recovery time of those who developed symptoms, rather than addressing the effectiveness of the vaccine in preventing infection.

Based on our analysis, the correct answer is D, as it resolves the apparent discrepancy by explaining that the vaccinated people who exhibited symptoms of hepatitis A were already infected before being vaccinated.