Question

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Explanation:

Analyze the introductory paragraph

The paragraph introduces how small rodents adapt the "subnivean zone" into their winter home. It describes how the zone is formed by grass supporting snowfall, creating a sturdy frozen roof with a constant temperature of 32 degrees Fahrenheit.

Evaluate the options for developing the topic

• Option 1 explains what the subnivean zone is (an insulated tunnel under the snow protecting animals from cold and predators), which directly defines the central term introduced in sentence (2) and developed in sentences (3)-(5).
• Option 2 focuses on animals in the first sentence, which are general examples of migration/hibernation, diverting focus from the subnivean zone.
• Option 3 focuses on specific diets of rodents, which is too narrow for an introduction.
• Option 4 is a vague statement about importance rather than concrete explanatory detail.

Determine the best fit

Option 1 provides the essential definition of the "subnivean zone" that is missing but highly necessary to clarify the topic for the reader in the introductory paragraph.

Answer:

• an explanation that the subnivean zone is an insulated tunnel under the snow that protects animals from the cold and other predators outside (Correct answer)
• a description of the animals mentioned in the first sentence to highlight the differences between animals that do and do not live in the subnivean zone
• a description of the rodents that live in the subnivean zone and what they will eat during winter
• a statement explaining why the subnivean zone is important