Question

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Explanation:

Analyze the core argument of the excerpt

The text explains that the flu shot prevents infections on a global scale "only if most people in the community take it" to achieve "herd immunity." It states that if too few people get the vaccine, it becomes less effective at protecting individuals. Conversely, when more people get the shot, the spread is prevented, making the vaccine more effective overall.

Evaluate the given options against the text

• Option 1 and Option 2 discuss "fewer people get the flu virus," which reverses the cause-and-effect relationship described in the text (the number of people getting the shot determines the spread of the virus, not the other way around).
• Option 3 states that as fewer people get the shot, it becomes more effective, which directly contradicts the text's explanation of herd immunity.
• Option 4 correctly states: "As fewer people get the flu shot, it becomes less effective, but as more people get it, the flu shot becomes more effective." This matches the text's explanation that vaccines need to reach enough people to be effective.

Answer:

• (A) As fewer people get the flu virus, the flu shot becomes less and less useful.
• (B) As fewer people get the flu virus, the flu shot becomes more and more useful.
• (C) As fewer people get the flu shot, it becomes more effective, but as more people get it, the flu shot becomes less effective.
• (D) As fewer people get the flu shot, it becomes less effective, but as more people get it, the flu shot becomes more effective. (Correct answer)