The student wants to define permafrost for an audience unfamiliar with the term. Which choice most effectively uses relevant information from the notes to accomplish this goal?

Question

While researching a topic, a student has taken the following notes:
- Permafrost is ground that stays frozen for at least two consecutive years.
- It underlies roughly 15 percent of the land in the Northern Hemisphere.
- It holds large amounts of carbon from ancient plant matter.
- When permafrost thaws, that carbon is released as greenhouse gases.

Accepted Answer

A. Permafrost is ground that remains frozen for at least two consecutive years, and it underlies roughly 15 percent of the land in the Northern Hemisphere.. A definition says what the thing IS. Choice A states the defining condition (frozen two consecutive years) and adds where it's found.

Answer

B. When permafrost thaws, greenhouse gases are released. — This describes what happens when permafrost thaws, and assumes the reader already knows what it is.

Answer

C. Permafrost holds carbon, which is why it underlies 15 percent of the land. — This invents a cause: holding carbon isn't why permafrost covers 15 percent of the land.

Answer

D. Greenhouse gases are released when frozen ground holds carbon. — This garbles the notes — gases are released when the ground THAWS — and never defines the term.

Expression of Ideas practice question

Answer: A. Permafrost is ground that remains frozen for at least two consecutive years, and it underlies roughly 15 percent of the land in the Northern Hemisphere.

Why the other answers are wrong

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