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Difficulty: MediumStrengthen

Municipal Administrator: In an effort to curb residential water waste during peak summer drought conditions, the city of Oakvale installed automated smart flow-meters in every home across District 4. Simultaneously, District 4 households were transitioned to a tiered pricing structure that imposed sharply higher per-gallon rates for usage exceeding a basic threshold. Over the following year, residential water consumption in District 4 decreased by 18 percent, whereas consumption in neighboring District 5, which retained flat-rate pricing and standard mechanical meters, remained unchanged. Therefore, the implementation of tiered pricing was the primary cause of the reduction in water waste in District 4.

Which of the following, if true, most strengthens the municipal administrator's argument?

  1. A
    During the observation period, the smart flow-meters alerted District 4 households to previously undetected underground plumbing leaks, the repair of which accounted for the vast majority of the volume saved.
  2. B
    Mandatory tiered pricing structures will invariably reduce residential utility consumption across all municipal jurisdictions regardless of local socioeconomic conditions.
  3. In an earlier municipal pilot program in District 4, installing automated smart flow-meters while maintaining the traditional flat-rate billing system resulted in no measurable decline in household water consumption.Answer
  4. D
    The mechanical water meters in District 5 suffered from gradual internal degradation that prevented them from registering minor month-to-month changes in water flow.
  5. E
    Households in District 5 possessed significantly larger average lot sizes and higher median incomes than households in District 4.

Answer

The statement establishing that deploying smart meters alone without tiered pricing yielded no measurable decrease in water use.
The conclusion asserts a specific causal relationship: tiered pricing caused the reduction in water waste. Because the city implemented two changes simultaneously (smart meters and tiered pricing), a major vulnerability of the argument is that the smart meters themselves might have caused the reduction. The correct answer provides control data showing that installing smart meters alone under flat-rate pricing had no effect on water consumption. By eliminating this competing causal explanation, the argument attributing the reduction to tiered pricing is significantly strengthened.

Step-by-Step Solution

1
Analyze the structure of the argument
Premises: District 4 received two simultaneous changes (smart meters and tiered pricing) and experienced an 18% drop in water use; District 5 had neither change and no drop. Conclusion: Tiered pricing was the primary cause of the reduction in District 4.
Deconstructing the argument into premises and conclusion is essential for identifying reasoning gaps.
2
Identify the primary logical vulnerability or assumption
The author assumes that the tiered pricing, rather than the simultaneous introduction of smart flow-meters or an unmentioned confounding factor, produced the observed 18% conservation.
When two potential causes are introduced simultaneously, attributing the effect entirely to one requires demonstrating that the other cause is not solely responsible.
3
Evaluate which supplementary statement best bridges the gap
Evidence demonstrating that smart meters in isolation did not reduce consumption effectively rules out the competing technological explanation, leaving pricing as the dominant operative cause.
Ruling out an alternative explanation directly increases the probability that the author's proposed cause is correct.

Key Concept

Strengthening Causal Arguments by Eliminating Confounding Variables
Estimated Time:1m 15s
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