Answer: The correct option is B
Explanation:
In Doppler effect, there is an apparent change in the frequency when there is a relative motion between the source and the listener.
Pitch depends on the frequency.
When the source and the listener are moving away from each other then there is decrease in the frequency. In this case, the pitch will be lower.
In the given problem, to drop the pitch of the horn relative to an observer, you would move the horn away from the observer.
Therefore, the correct answer is "Away from the observer".
