two sound sources are moving in oppostive directions with velocities ` v_(1) and v_(2) ( v_(1) gt v_(2))` . Both are moving away from a stationary observer. The frequency of both the sources is 900 Hz. What is the value of ` v_(1) - v_(2)` so that the beat frequency aboserved by the observer is 6 Hz. speed of sound v= 300 m/s given ,that `v_(1) and v_(2) lt lt v `
A. 1m/s
B. 2m/s
C. 3m/s
D. 4 m/s