A source and an observer are situated on two perpendicular tracks as shown in the figure the observer is at rest and source is moving with a speed `50m//s` the source emits sound waves of frequency 90Hz which travel in the medium with velocity `200m//s` the frequency of sound heard by observer when the source crosses the origin is

Options

A. 70 Hz
B. 80 Hz
C. 96 Hz
D. 85 Hz

Answer

B