Children must be restrained with proper child-restraint equipment until they reach what height or age?

The correct answer is based on the combination of height and age requirements for child restraint systems. Children must use proper child-restraint equipment until they reach either 150 centimeters in height or 12 years of age. This dual requirement ensures that children are adequately protected in vehicles, as both height and age can influence their physical development and the effectiveness of safety restraints.

It is essential to have these guidelines in place because a child's size and maturity directly impact their safety during travel. Height is a crucial factor since seat belts and vehicle seats are designed for certain dimensions; exceeding the height limit may indicate that a child no longer fits safely within a child restraint system. Similarly, age plays a critical role since younger children require specialized restraints to ensure they are secured appropriately in the event of a collision.

In this context, the other choices either focus exclusively on height or age, which may not provide comprehensive coverage of the safety requirements outlined. Therefore, the most accurate option combines both criteria, making it imperative to adhere to both the height and age requirements for child restraints.