Two Cars Are Traveling in the Same Direction and with the Same

Multiple Choice

Two cars are traveling in the same direction and with the same speed along a straight highway. Does either driver hear a different frequency from the other car's horn than they would if the cars were stationary?

A) They both experience a Doppler shift.
B) Only the driver of the front car experiences a Doppler shift.
C) Only the driver of the rear car experiences a Doppler shift.
D) No, because neither driver experiences a Doppler shift.
E) It is impossible to predict.