How does dynamic axle load transfer (dynamische Achslastverlagerung) affect vehicle handling during heavy emergency braking?

1. Weight shifts forward to the front axle, increasing front tire vertical load and grip while unloading the rear axle, which increases rear instability
2. Weight shifts entirely to the rear axle, causing the front wheels to lift into the air
3. Axle load remains perfectly static and identical at all times
4. Weight shifts exclusively to the left side of the vehicle