The continent of antarctica is covered with an ice sheet. which part of the earth system includes the ice sheet?
a. biosphere
b. cryosphere
c. hydrosphere
d. atmosphere

These factors threaten north americas ecosystems

Aplane cuts a pyramid as shown in the diagram. what is the shape of the cross section? a. a hexagon b. a pentagon c. a square d. a triangle

Which of the following best describes the purpose of a nation’s boundaries? a. to limit the movement of goods and people b. to make it easier for cartographers to create maps c. to make the movement of goods and people easier d. to prevent other countries from invading territory