What physical phenomenon occurs during 'Understeering' (Untersteuern) in a vehicle, and how should a driver properly correct it?

1. The rear tires lose grip and the tail slides outward; correct by accelerating hard in the opposite direction
2. The front tires lose grip and the vehicle pushes straight ahead towards the outside of the curve; correct by gently reducing steering lock and easing off the accelerator to restore front tire adhesion
3. The vehicle flips onto its roof immediately
4. The brakes lock up completely and require pulling the mechanical emergency handbrake