The mean sustained wind velocity, $v$, can be determined by the equation $v=6.3 \sqrt{1013-p}$, where $p$ is the air pressure, in millibars, at the center of the hurricane. What is the approximate air pressure at the center of a hurricane when the mean sustained wind velocity is 64 meters per second?

A103 millibars

B194 millibars

C363 millibars

D910 millibars