Why is it dangerous if passengers sitting in the rear do not wear their seatbelts?

All three answers are correct. If passengers in the back seat do not wear their seatbelts, they put themselves at risk of injury even at low speeds because, during a sudden stop or collision, their bodies may be thrown forward uncontrollably. This impact can also cause injuries to passengers in the front seats, as unbelted rear passengers can hit them. In severe accidents, unbelted passengers may even be thrown out of the vehicle. That's why everyone in the car must always use their seatbelt for safety. This rule helps protect all occupants in the event of a crash.