Using new detection techniques, researchers have found trace amounts of various medicinal substances in lakes and rivers. Taken in large...
GMAT Critical Reasoning : (CR) Questions
Using new detection techniques, researchers have found trace amounts of various medicinal substances in lakes and rivers. Taken in large quantities, these substances could have serious health effects, but they are present in quantities far too low to cause any physiological response in people who drink the water or bathe in it. Nevertheless, medical experts contend that eliminating these trace amounts from the water will have public health benefits, since _______________.
Which of the following most logically completes the passage?
Passage Analysis:
| Text from Passage | Analysis |
| Using new detection techniques, researchers have found trace amounts of various medicinal substances in lakes and rivers. |
|
| Taken in large quantities, these substances could have serious health effects, but they are present in quantities far too low to cause any physiological response in people who drink the water or bathe in it. |
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| Nevertheless, medical experts contend that eliminating these trace amounts from the water will have public health benefits, since ________. |
|
Argument Flow:
We start with a discovery (trace medicines in water), then learn these amounts seem harmless to humans, but experts still want them removed for health benefits. The argument sets up a contradiction that needs explaining.
Main Conclusion:
Medical experts believe eliminating trace medicinal substances from water will benefit public health (the blank needs to explain why)
Logical Structure:
The passage creates a puzzle: if trace amounts don't harm humans directly, there must be another reason why removing them helps public health. We need to find the missing link that explains this apparent contradiction.
Prethinking:
Question type:
Logically Completes - We need to find a reason that explains why medical experts think removing harmless trace amounts of medicines from water will benefit public health
Precision of Claims
The passage establishes specific quantities (trace amounts vs large quantities) and effects (no current physiological response vs potential serious health effects). We need to respect these precise boundaries while finding logical completion
Strategy
Since the experts believe removal will help despite current harmlessness, we need scenarios that explain this apparent contradiction. The completion should provide a logical bridge between 'currently harmless' and 'removal benefits public health.' We should look for indirect effects, long-term concerns, or situations where even trace amounts matter in ways not covered by immediate physiological responses
This choice tells us that some medicines are harmless even in large quantities. But this doesn't help explain why experts want to remove trace amounts - if anything, this would make removal seem even less necessary. The passage already establishes that trace amounts don't harm people directly, so knowing some medicines are harmless in large quantities doesn't provide any new reason for removal.
This suggests some medicines can counteract harmful effects of others in the water. While this might seem relevant, it doesn't explain why experts want to eliminate all trace amounts. If some substances counteract harmful effects, this would actually argue against removal, not for it.
This talks about changing treatment when patients have side effects from medicines. This is completely irrelevant to the question of why we should remove trace amounts from water sources. We're not discussing medical treatment protocols - we're discussing environmental contamination.
This tells us that most medicinal substances break down into harmless substances quickly. If this were true, it would actually argue against the need for removal since the problem would solve itself naturally. This doesn't support the experts' position at all.
This explains that bacteria exposed to low concentrations of medicines can become resistant to them. This is the perfect explanation! Even though trace amounts don't directly harm humans, they can create antibiotic-resistant bacteria, which is a major public health threat. When bacteria become resistant to our medicines, those medicines become less effective when we actually need them to fight infections. This provides a compelling reason why removing even harmless trace amounts benefits public health.