A 30 ft ladder is leaning against the side of a building. You pull the base of the ladder away from the wall of the building at a rate of 9 in/sec . At what rate is the height of the ladder above the ground changing when the base of the ladder is 10 feet from the wall of the building?

A. -0.75 ft/sec
B. -0.265 ft/sec
C. 449.25 ft/sec
D. 15.645 ft/sec