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Difficulty: MediumCommand of Evidence: Textual

Glaciologist Dr. Hiroshi Tanaka investigated the impact of windborne dust on glacier melting in the Southern Alps. Tanaka hypothesized that dust particles originating from neighboring agricultural fields deposit onto glacier surfaces, lowering the glaciers' albedo—their capacity to reflect solar radiation—and consequently accelerating surface melting during the summer. To test this hypothesis, Tanaka's team monitored several glaciers, measuring both surface dust concentration and reflectivity alongside local temperature changes. Which choice, if true, would most directly support Tanaka's hypothesis?

  1. A
    Soil samples collected from agricultural fields near the Southern Alps contained organic nutrients that promote the growth of ice-dwelling algae, which can also affect glacier color.
  2. B
    Agricultural dust emissions in the region are projected to increase over the next century due to changing wind patterns, potentially altering the regional climate.
  3. Glaciers with the highest concentrations of agricultural soil particles on their surfaces exhibited a marked decline in albedo and experienced significantly greater volume loss than cleaner glaciers under identical temperature conditions.Answer
  4. D
    Glaciers with lower levels of surface dust showed an increase in melting rates whenever daytime temperatures exceeded historical averages.

Answer

The correct answer is the option stating that glaciers with the highest concentrations of agricultural soil particles on their surfaces exhibited a marked decline in albedo and experienced significantly greater volume loss than cleaner glaciers under identical temperature conditions.
The correct answer provides direct empirical support for the glaciologist's hypothesis. It links the presence of agricultural soil particles on glacier surfaces to both a decrease in albedo (reflectivity) and an increase in melting (measured as volume loss) under identical temperature conditions, confirming the proposed cause-and-effect relationship.

Step-by-Step Solution

1
Identify the researcher's hypothesis in the passage.
Tanaka hypothesized that agricultural dust deposits onto glaciers, lowers their albedo (reflectivity), and accelerates surface melting during summer.
Understanding the precise claim is necessary to identify what evidence would support it.
2
Determine the required evidence to support this hypothesis.
The evidence must demonstrate that higher concentrations of agricultural dust on glaciers correlate with lower reflectivity (albedo) and increased melting, ideally when temperature is controlled.
This establishes the causal chain proposed by the hypothesis.
3
Evaluate the choices against the required evidence.
The choice describing glaciers with high dust concentrations exhibiting lowered albedo and greater volume loss under identical temperatures directly supports the hypothesis.
It confirms the correlation between the dust concentration, albedo decline, and accelerated melting.

Key Concept

Command of Evidence: Textual
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Command of Evidence: Textual

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