A detector far away from the source of a wave is detecting pulses of that wave every 0.2 second. If the detector starts to move towards the source at a speed of 6.0 km/h, then it would detect a total of 18200 pulses per hour. What is the speed of the wave?
a) 100 m/s
b) 150 m/s
c) 200 m/s
d) 300 m/s