What is the purpose of using a liner in a fiberboard box?

Using a liner in a fiberboard box primarily serves to strengthen the box's structure. This reinforcement is crucial, especially when the box is used to transport heavy or fragile items. A liner can enhance the rigidity of the box, preventing collapse or deformation under stress. Additionally, the liner can help maintain the integrity of the contents by providing a more stable environment, which is essential for protecting items during transit.

The other choices, while they might offer some advantages in specific contexts, do not capture the main purpose of a liner effectively. For example, increasing aesthetic appeal or providing insulation can be secondary benefits but are not the primary reasons for using a liner in fiberboard boxes. Similarly, while a liner may contribute to cost savings in some indirect way by preventing damage, that is not its fundamental purpose. The focus remains on the structural enhancement that a liner provides in ensuring safe and effective packaging.