The Wind's Speed Generally Increases with Height Above the Earth's

Multiple Choice

The wind's speed generally increases with height above the earth's surface because

A) only the lowest layer of air rotates with the earth.
B) air temperature normally decreases with height.
C) wind instruments are not accurate at the earth's surface.
D) friction with the earth's surface slows the air near the ground.
E) air parcels expand and become less dense as they rise above the surface.