There is a close relationship between the air pressure inside a hurricane and its maximum sustained wind speed: y=−1.22x+1250 where x is the air pressure in millibars (kPa) and y is the wind speed in knots (nautical miles per hour). What does the slope of the line represent?

A. the wind speed of a hurricane with an air pressure of 0 kPa
B. the change in wind speed for every hour
C. the change in wind speed for every 1 kPa increase in air pressure
D. the wind speed of a hurricane with an air pressure of 1000 kPa