When should you flash your brake lights?

Answer: C — When slowing down, encountering trouble ahead, making tight turns, or stopping on the road

Flashing your brake lights is not limited to only when stopping on the road (option A) or making tight turns (option B). It should be done in a variety of situations, such as slowing down, encountering trouble ahead, making tight turns, or coming to a complete stop on the road (option C). This ensures that other drivers are aware of your actions and helps prevent accidents. Option D, only flashing your brake lights when slowing down, is not as comprehensive as option C and may not alert other drivers to potential hazards.