Compared to people who live in other environments - PR-test

[KM]

Source: Princenton Review - Sample test

Compared to people who live in other environments, people who live in urban areas have high rates of infection. Such people also have among the lowest levels of physical fitness. Clearly, infection can result from low levels of physical fitness.

Which of the following, if true, most seriously weakens the argument above?

a) Rates of infection vary widely among different urban areas.

b) People who live in urban areas are exposed to extreme concentrations of pollutants, which are known to cause infection.

c) Many people who live in urban areas have high levels of physical fitness.

d) Some of the cases of infection in people who are very physically fit are not documented.

e) Infections are the most infrequently occurring form of illness in either rural or urban areas.

As per the test, answer is b. Why not d ? No where in b does it relate to fitness..

Pls help
-KM

[tryinhard]

premise states that people in urban areas have 'high rate of infection' & such people have 'low level of physical fitness'
C:infection can result from low level of physical fitness

However, premise does not specify which comes first 'infection 'or 'low level of physical fitness'

to weaken
1) if we can say- infection results into low levels of physical fitness- weakens conclusion

i think B does the same
a)out of scope(rates of infection)
c)wrong
d)wrong(because not affecting conclusion)
e)wrong

so we are left with b

plz contribute

[SAN]

Here author depicts one model of infection that is result from physical fitness.

But there can be other models that can cause the infections such as mentioned in B.

By depicting the model B, author is weakening the statement.

[esledge]

My diagram on this one is similar to the above. It can be a good practice to jot down your doubts about the argument BEFORE you get mired in the misleading language of the choices.

P1: Urban = High Infection
P2: Urban = Low Fitness
C: Low Fitness --> Infection.
Doubts: Even if Infection and Fitness relate to Urban dwelling, couldn't they be unrelated to each other? Even if Infection and Fitness are related to each other, that doesn't necessarily mean that one CAUSED the other...

(a) Rates of infection vary widely among different urban areas: Suggests that P1 is simplified statement, but does not contradict P1. Does not directly relate to conclusion.

b) People who live in urban areas are exposed to extreme concentrations of pollutants, which are known to cause infection: Suggests an alternate cause of infection, which directly relates to C.

c) Many people who live in urban areas have high levels of physical fitness: Suggests exceptions to P2 exist, but does not contradict generality of P2. Does not directly relate to conclusion.

d) Some of the cases of infection in people who are very physically fit are not documented: Suggests there is missing info on P1/P2 overlap. Does not directly relate to conclusion.

e) Infections are the most infrequently occurring form of illness in either rural or urban areas: Attempts to expand P1 with data about frequency and rural areas. Does not directly relate to conclusion.

Note how the wrong answers all focus on the Premises, while the right answer focuses on the Conclusion and/or the missing link between Conclusion and Premises!