Compared to people who live in other environments, people who live in

Argument : Based on 2 facts
1.Urban people suffers from Infection
2. Urban people lack physical fitness

Conclusion: infection can result from low levels of physical fitness.
Assumption: No other factor cause the infection

Weakness : Possible answer choice will be make the conclusion less believable by removing strengthening points or break the assumption.

Choice Analysis:
A. Rate of infection on different urban people does not weaken the conclusion.
B. Break the assumption, so it is the correct answer
C. Answer choice try to confuse us with using similar words, though many people are fit in urban area , but that does not weaken the argument that Infection result from lack of fitness. out of scope
D. Again out of scope "some" can be 1 to n
E. Out of scope

In order to weaken the conclusion we would need information that would indicate the infection is from another source than lack of physical fitness.

B) People who live in urban areas are exposed to extreme concentrations of pollutants, which are known to cause infection.
This is the only answer choice that suggests the infection is from another source.

How to assume number for words many, most and others?
As All = 100% & None = 0%.

Conclusion: Clearly, infection can result from low levels of physical fitness.

Premise: People who live in urban areas have high rates of infection. Such people also have among the lowest levels of physical fitness.

Assumption: (1) It's not a coincidence. It’s not a coincidence that people who live in urban areas and have high rates of infection also have low levels of physical fitness. (2) There's no other cause. Nothing else but low levels of physical fitness caused the high rates of infection.

The phrase, most seriously weakens, in the question stem identifies this as a weaken question. Identify the conclusion, premises, and assumption. The indicator word, clearly, in the last sentence points toward the conclusion of the passage, infection can result from low levels of physical fitness. The phrase can result from indicates that this is a causal pattern. The premises of the argument, people who live in urban areas have high rates of infection. Such people also have among the lowest levels of physical fitness, provide a correlation between high rates of infection and low levels of physical fitness.

The standard assumptions of a causal reasoning pattern are that it’s not a coincidence and there’s no other cause. Because this is a weaken question, the correct answer will attack one of these assumptions. For example, the correct answer may show that the correlation between infection and residence in urban areas is only a coincidence by providing a counterexample. The correct answer could also break the causal link by introducing an alternate cause for the high rates of infection for people who live in urban areas. Evaluate the answer choices, looking for one that reflects either of these ideas.

Choice A: No. The phrase Rates of infection vary widely is out of scope. There could still be a high level of infection in all cities, even with the variation. This new information does not weaken the link between high levels of infection and low levels of physical fitness because this choice does not provide a counterexample or an alternate cause.

Choice B: Correct. This answer choice weakens the argument by providing another possible cause for the high rate of infection—exposure to extreme concentrations of pollutants—that is not related to physical fitness levels.

Choice C: No. High levels of physical fitness is out of scope. The passage is concerned with people who live in urban areas who have high rates of infection. Even if many people who live in urban areas have high levels of physical fitness, the link between high rates of infection and low levels of physical fitness is not weakened because this choice does not provide a counterexample or an alternate cause.

Choice D: No. Cases of infection in people who are very physically fit is out of scope. The passage is concerned with people who live in urban areas who have high rates of infection and have among the lowest levels of physical fitness.

Choice E: No. The most infrequently occurring form of illness is out of scope. The passage is not concerned with the frequency of forms of illness in rural or urban areas. This choice does not provide a counterexample or an alternate cause.

The correct answer is choice B.

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