What feature is crucial for securing younger passengers in a vehicle?

The feature that is crucial for securing younger passengers in a vehicle is the child restraint system. This system is specifically designed to protect children in the event of a collision and to ensure their safety while traveling. It includes devices such as car seats and booster seats, which provide proper support and positioning for the child according to their age, weight, and height. Using a properly installed child restraint system significantly reduces the risk of injury or fatality in an accident.

While child locks enhance safety by preventing rear doors from being opened while the vehicle is in motion, they do not directly secure passengers. The luggage compartment is designed for storage, and a rearview camera assists with visibility while reversing but does not involve passenger safety. Thus, the child restraint system stands out as the essential feature for safely securing younger passengers.