Answer:
Frequency will be 485 Hz
So option (c) will be the correct option
Explanation:
We have given frequency f = 500 Hz
Velocity of observer [tex]v_o=20m/sec[/tex]
Velocity of source [tex]v_s=10m/sec[/tex]
When both observer and source are moving then frequency is given by
[tex]f'=\frac{v-v_o}{v-v_s}\times f[/tex] , here v is the velocity of sound
So [tex]f'=\frac{340-20}{340-10}\times 500=485Hz[/tex]
So option (c) will be the correct option