Which term refers to permanently frozen ground consisting of soil, rock, and ice that remains below freezing for at least two consecutive years?

• A. Cryosphere
• B. Ice sheet
• C. Permafrost
• D. Glacier

Answer: (C)

Permanently frozen ground refers to permafrost—a layer of soil, rock, and ice that remains at or below freezing for at least two consecutive years. This definition distinguishes permafrost from other frozen features because it specifically describes ground that stays frozen over time, with ice embedded in the soil and rock.

While the cryosphere includes all of Earth's frozen components (ice caps, glaciers, sea ice, and permafrost), the term here points to the ground itself, not the entire frozen system. An ice sheet is a massive, thick sheet of ice that covers large land areas (like Antarctica or Greenland) and doesn’t imply the surrounding soil is permanently frozen. A glacier is a flowing river of ice formed from accumulated snow; it also does not describe the permanently frozen ground. Therefore, permafrost best matches the description given.