When must you use your horn?

Using your horn is primarily intended as a safety device to communicate with other road users. The correct answer emphasizes the importance of honking to alert others in potentially dangerous situations. This means when you see someone or something that could lead to an accident or when you are unsure if another driver or pedestrian can see you, using your horn can help prevent collisions by making your presence known.

In contrast, honking to greet other drivers is not a practical or recommended use of the horn, as it can lead to confusion and disrupt the flow of traffic. The horn is also not meant to be used when merely approaching a traffic signal, as this does not typically constitute a dangerous situation. Lastly, restricting horn usage only to nighttime is not in line with driving safety practices. The horn should be available for use at any time during the day when safety is at risk.