What action should you take if your brakes fail while driving?

Using the emergency brake cautiously is the correct action to take if your brakes fail while driving. The emergency brake, also known as the parking brake, is an additional braking system that can help slow down or stop the vehicle when the primary brakes fail. Applying the emergency brake gradually allows you to avoid skidding and losing control of the vehicle. It is crucial to use this brake gently to prevent locking the rear wheels, which could lead to further loss of control.

The other choices present actions that may not be as effective or safe in a situation where brakes have failed. Turning off the engine could result in losing power steering and power brakes, making the vehicle much harder to control. Steering into a ditch might be considered in extreme situations, but it could also lead to a more dangerous crash. Shifting into neutral would allow the vehicle to coast but does not actively address the lack of brakes and may prolong the problem, making it harder to regain control. Employing the emergency brake is a direct response that actively helps bring the vehicle to a stop safely.