In the Doppler Effect for Electromagnetic Waves,which of the Following

Multiple Choice

In the Doppler effect for electromagnetic waves,which of the following gives the greatest shift in frequency?

A) the source moving toward the non-moving observer at speed v
B) the observer moving toward the non-moving source at speed v
C) the source moving toward the approaching observer,both at speed v/2
D) All of the above give the same shift.