Question

The change in frequency due to Doppler effect does not depend on
(a) the speed of the source
(b) the speed of the observer
(c) the frequency of the source
(d) separation between the source and the observer.

Answer 1

(d) separation between the source and the observer

$v_0=\left(\frac{v\pm u_0}{v\pm u_s}\right)v_s$
It is clear from the equation that the change in frequency due to Doppler effect depends only on the relative motion and not on the distance between the source and the observer.