Which of the following statements about the movement of earth's atmosphere is correct? select one:

a. a column of warm, less dense air produces high pressure at the earth's surface.
b. cold air is less dense than cool air so it tends to sink toward the earth's surface.
c. the movement of air within the atmospheric convection cells generates the wind belts.
d. warm air is denser than cool air so it tends to sink toward the earth's surface.
e. a column of cool, dense air produces low pressure at the earth's surface.