Under what circumstance is it acceptable to use your horn?

Using your horn is primarily intended as a safety device to alert others to potential dangers. In situations where you believe your life is in danger, using your horn can serve as a crucial warning signal to alert other drivers and pedestrians to your presence, especially if you are in a precarious situation that might lead to an accident. This use aligns with the intended purpose of the horn, which is to promote safety on the road.

In contrast, using your horn to alert pedestrians of your presence may not always be necessary or appropriate, as it can cause confusion or panic rather than safety. Expressing frustration or using the horn in congested areas when parked does not contribute positively to traffic safety and may escalate tensions rather than mitigate dangers. Therefore, the correct circumstance for horn use from the given choices emphasizes the importance of safety above all else.