You're driving in fog. When should you switch on your rear fog lights? You're driving in fog. When should you switch on your rear fog lights?

• Possible answers:

   
• A. When visibility has fallen to your overall stopping distance
• B. When visibility has fallen to 10 car lengths
• C. When visibility has fallen to 100 metres (328 feet) or less
• D. When visibility has fallen to 200 metres (656 feet) or less