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Difficulty: MediumIdentifying Core Claims and Hypotheses

### Venusian Resurfacing

The surface of Venus has remarkably few impact craters, suggesting a relatively young surface age of 300 to 600 million years. Scientists agree that volcanism is responsible for erasing older craters, but they debate the timeline and nature of this resurfacing.

*Hypothesis 1*
Venus experiences episodic, global volcanic events. Because Venus lacks Earth-like plate tectonics, internal heat cannot escape steadily. Instead, heat builds up in the mantle over hundreds of millions of years, eventually causing the lithosphere to weaken and overturn. This leads to rapid, planet-wide volcanic resurfacing within a span of less than 100 million years, followed by a long period of geological inactivity during which heat accumulates again.

*Hypothesis 2*
Venus undergoes gradual, localized resurfacing. The planet is geologically active, with continuous but small-scale volcanic eruptions and tectonic deformation occurring in various regions at different times. Over hundreds of millions of years, these scattered, ongoing events gradually bury and erase older craters, maintaining a young average surface age without requiring a single, catastrophic global event.

Which of the following statements best summarizes the core claim of Hypothesis 2 regarding the resurfacing of Venus?

  1. The surface is renewed through steady, ongoing volcanic and tectonic processes occurring in localized areas.Answer
  2. B
    The surface is renewed through sudden, global volcanic events triggered by mantle heat buildup.
  3. C
    The surface is renewed through the continuous subduction and movement of global tectonic plates.
  4. D
    The surface is renewed by intense solar radiation melting the crust in a uniform, planet-wide pattern.

Answer

The surface is renewed through steady, ongoing volcanic and tectonic processes occurring in localized areas.
The correct answer states that the surface is renewed through steady, ongoing volcanic and tectonic processes occurring in localized areas. This matches Hypothesis 2, which argues that resurfacing on Venus happens gradually via continuous, localized, small-scale volcanic and tectonic activity rather than a single global catastrophe.

Step-by-Step Solution

1
Identify the target viewpoint in the question.
The question asks for the core claim of Hypothesis 2.
Focusing on the correct hypothesis prevents misattributing claims from Hypothesis 1.
2
Locate the description of Hypothesis 2 in the passage and summarize its main mechanism.
Hypothesis 2 describes 'gradual, localized resurfacing' driven by 'continuous but small-scale volcanic eruptions and tectonic deformation occurring in various regions.'
This establishes the factual basis for identifying the correct summary.
3
Compare the summary of Hypothesis 2 with the given options.
The option stating that resurfacing occurs through steady, localized processes directly matches the description of Hypothesis 2, while other options describe Hypothesis 1, introduce plate tectonics, or mention unrelated processes like solar radiation.
This determines the correct option by elimination and direct matching.

Key Concept

Identifying Core Claims and Hypotheses
Estimated Time:1m 0s
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Topics

Identifying Core Claims and Hypotheses

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