Two sound sources are moving in opposite directions with velocities `v_1` and `v_2(v_1gtv_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 observed by the observer is 6 Hz? Speed of sound `v=300(m)/(s)`. Given that `v_1` and `v_2ltltltv`.
A. `1(m)/(s)`
B. `2(m)/(s)`
C. `3(m)/(s)`
D. `4(m)/(s)`