Why must a driving instructor discuss both mass and load placement when a passenger vehicle is heavily loaded?

1. Only tire pressure changes; handling is otherwise identical
2. Additional mass changes acceleration and braking demands, while a high or uneven load can raise or shift the center of gravity and reduce cornering or evasive stability
3. A full load always lowers the center of gravity regardless of where baggage is placed
4. Electronic stability control removes the need to observe payload and axle limits