this question is from LSAT Prep Test 19, Section 4, Question 1. The correct answer has to be D. Please change it in the question.
Let us simplify the argument given --
Premise1. Sara and Michael both ill and have same symptoms
2. they play together every afternoon
3. Hence, they probably have the same illness
4. Michael does not have streptococcal infection (despite having some symptoms of that infection)
ConclusionSara definitely does not have a streptococcal infection
Note that there is a shift from "probably have the same illness" to the conclusion "definitely does not have streptococcal infection".
This is the error in reasoning here -- which answer option mentions this?
Option D.Let us look at other answer options --
Option A - Incorrectthe argument does not exactly presuppose what it concludes -- the premise talks about a "probable" event, the conclusion "definite" event.
Option B - IncorrectCause and effect scenario is mentioned here in points 2 and 3 --
play together --> probably have the same diseaseNo mistaking effect for cause is done here.
Option C - Incorrect"acute vs less severe" is irrelevant to the conclusion
Option E - IncorrectWe are not "generalizing" from the cases of Michael and Sara.