A sound source of constant frequency travels with a constant velocity past an observer. When it crosses the observer the sound frequency sensed by the observer changes from 449 Hz to 422 Hz. If the velocity of sound is 340 m/s, the velocity of the source of sound is

A

8.5 m/s

B

10.5 m/s

C

12.5 m/s

D

14.5 m/s