In which of the following situations should you not use your horn?

Answer: C — When a pedestrian is in the crosswalk

A horn should not be used when a pedestrian is in the crosswalk because this can startle or scare the pedestrian, potentially causing them to panic or make a mistake while crossing the street. A loud horn can also be seen as aggressive or intimidating in this situation. While it may be tempting to honk at a driver who cuts you off, it is not an appropriate or safe use of a horn. It is also not necessary to use a horn when driving at low speeds, as honking is generally used as a warning signal at higher speeds. If it is safe to pass another vehicle, it is not necessary to honk as passing itself is a signal to the other driver that you are about to overtake them.