On a motorway, when should a driver use the hazard warning lights?

When parked in the hard shoulder to take a phone call.
When another vehicle is following too closely.
When the vehicle has broken down.
When towing another vehicle.

Explantion: Use the hazard warning lights to warn other road users of a danger ahead. For example, if your vehicle has broken down and is stopped on the hard shoulder, you can use the hazard warning lights to warn following vehicles of your presence.

Theory Tester

On a motorway, when should a driver use the hazard warning lights?

Legal Matters/Rules of the Road