UK Driving Theory Practice Exam

Using your horn and flashing headlights should only be done when necessary, such as to alert others of your presence in a potentially dangerous situation. Using them for any other reason, such as making a statement or responding to aggressive drivers, may cause unnecessary noise and distractions on the road. Additionally, using them in non-residential areas where there are fewer drivers and pedestrians may not be necessary. So, option A is the only appropriate reason to use your horn and flashing headlights.