The surface pressures at the bases of warm and cold columns of air are equal. Which of the following describes the air pressure in the warm column of air compared to the air pressure in the cold column?

(a) It increases with increasing height more slowly than in the cold column.
(b) It increases with increasing height more rapidly than in the cold column.
(c) It decreases with increasing height more rapidly than in the cold column.
(d) It decreases with increasing height more slowly than in the cold column.