At a constant temperature of 15˚C, the barometric pressure can be approximated by the formula P=1013.25(0.89)x, where x is the altitude above sea level, measured in kilometers. Which of the following statements bests describes how the pressure is changing?

A. The pressure decreases by 89% every for every addition km above sea level.
B. The pressure increases by 89% every for every addition km above sea level.
C. The pressure increases by 11% every for every addition km above sea level.
D. The pressure decreases by 11% every for every addition km above sea level.