When may hazard warning lights be used while driving? When may hazard warning lights be used while driving?

• Possible answers:

   
• A. To thank a driver who has let you move back to the left after overtaking
• B. As a warning to drivers that you're towing another vehicle
• C. To show you want to go ahead when your position suggests otherwise
• D. When on motorways or dual carriageways, to warn drivers behind of a hazard ahead