Which is a definition of "severe wind shear?"

A. Any rapid change of horizontal wind shear in excess of 25 knots; vertical shear excepted.

B. Any rapid change in wind direction or velocity which causes airspeed changes greater than 15 knots or vertical speed changes greater than 500 ft/min.

C. Any change of airspeed greater than 20 knots which is sustained for more than 20 seconds or vertical speed changes in excess of 100 ft/min.