What is the primary danger of transporting liquid cargo in a partially filled tanker truck with no internal baffles (cisterna sin rompeolas / tanque con oleaje libre)?

1. Liquid turns into solid ice instantly
2. Liquid slosh (oleaje libre o efecto ola) creates massive dynamic surging: forward sloshing pushes the truck during braking, and lateral sloshing shifts the center of gravity violently in curves, causing rollovers
3. The liquid will evaporate through the tires
4. It makes the truck completely silent