Which of the following is true about ice sheets?

a. They are the smallest type of glacier.

b. They flow in all directions.

c. They usually flow down valleys.

d. They are found only in high mountain areas.

Answer:c. They usually flow down valleys.

Explanation:Ice sheets are constantly in motion, slowly flowing downhill under their own weight. Near the coast, most of the ice moves through relatively fast-moving outlets called ice streams, glaciers, and ice shelves. As long as an ice sheet accumulates the same mass of snow as it loses to the sea, it remains stable.