Final answer:
Upon hearing an emergency vehicle siren while driving, you should pull over to the right and stop, utilizing the Doppler shift to determine the siren's location.
Step-by-step explanation:
When driving on a two-way road and hearing an emergency vehicle siren, the correct course of action is A) Pull over to the right side of the road and stop. This response ensures that you are following the law and providing a clear path for the emergency vehicle to pass. Utilizing the Doppler shift, a change observed in the frequency or pitch of the siren's sound as it approaches or moves away from you, can alert you to the vehicle's location and motion. This auditory cue helps you determine when the emergency vehicle is getting closer and when it has passed by, guiding your decision to safely pull over.