The Doppler shift may be helpful for someone trying to _______.

A) overcome a visual illusion
B) block out irrelevant noises
C) locate sounds
D) see an object in very dim light

The Doppler shift is a change in frequency or pitch that occurs when there is relative motion between a sound source and an observer. By detecting this shift, an observer can determine the location of a sound source. Therefore, the Doppler shift may be helpful for someone trying to locate sounds.