What is a “booster seat”?

1. Correct answer: A seat that is designed for transporting small children, restrained by the safety belt of the vehicle.
2. A standard seat that is designed for transporting children until 18 years of age
3. A seat that is designed for a driver whose height is less than 160 cm and whose age is more than 18 years
4. A seat that is designed for transporting children on bicycles only while the children are restrained by a safety belt.

WhyA booster raises the child so the car's own seat belt sits correctly on them. It has nothing to do with bicycles or adult drivers.