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Difficulty: MediumLogical Inferences

In glaciology, cryophilic algae thrive on glacier surfaces during melting seasons. To protect themselves from intense ultraviolet radiation, these algae produce dark-colored pigments. However, these pigments also reduce the albedo—or reflectivity—of the ice surface, causing it to absorb more solar radiation. Researchers investigating the Greenland Ice Sheet observed that areas with high densities of cryophilic algae experienced melting rates that significantly exceeded predictions based solely on regional atmospheric temperatures. Since regional air temperatures remained stable, this discrepancy suggests that ______

Which choice most logically completes the text?

  1. A
    solar radiation is a more significant driver of global glacial melting than atmospheric temperature is.
  2. B
    cryophilic algae will eventually migrate to other ice sheets as global temperatures continue to rise.
  3. the presence of cryophilic algae directly accelerated the ice melt by increasing the absorption of solar radiation.Answer
  4. D
    areas of the Greenland Ice Sheet with low algal density did not experience any melting during the study period.

Answer

the presence of cryophilic algae directly accelerated the ice melt by increasing the absorption of solar radiation.
The correct answer is correct because the passage directly links the algae's dark pigments to decreased reflectivity and increased solar absorption, which explains the accelerated melting rate that occurred independent of atmospheric temperature changes.

Step-by-Step Solution

1
Identify the core premises in the passage.
The passage establishes that cryophilic algae produce dark pigments that decrease reflectivity (albedo) and increase solar radiation absorption. High-density algae areas melted faster than predicted by temperature alone, while regional temperatures remained stable.
Establishing the facts and relationships presented in the text is necessary to draw a logical conclusion.
2
Analyze the discrepancy in the melting rate.
The melting rate exceeded predictions based on temperature, but temperatures were stable, pointing to a non-temperature factor.
This isolates the albedo-reduction effect of the dark pigments as the variable driving the accelerated melting.
3
Formulate a conclusion that ties the premises together without introducing outside assumptions.
The algae's presence and pigments directly accelerated the ice melt by increasing the absorption of solar radiation.
This is the only direct, non-speculative inference supported by the premises.

Key Concept

Logical Inferences
Estimated Time:1m 30s
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Logical Inferences

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