use controlled or stab braking.
Hard braking and turning at the same time is likely to cause a skid. You should brake in a way that will keep your vehicle in a straight line and allow you to turn if it becomes necessary. If you need to brake suddenly to avoid a crash, use controlled braking or stab braking (but don't use stab braking if your vehicle has antilock brakes).
B push the brake pedal as hard as you can and hold it there.
C use only the trailer brakes.