A sub-front is:

A sub-front serves as the structural element of a drawer box located behind the visible drawer front. This component provides support and strength to the drawer, ensuring that it can handle the loads imposed by the items stored within. It also plays a crucial role in the installation and functionality of the drawer, helping to secure the drawer front to the rest of the drawer assembly.

The other options describe elements that are not related to the function of a sub-front. For instance, a falsely depicted drawer face refers to a design feature, rather than a structural component, and a kick plate is an entirely different item used at the bottom of kitchen cabinets or structures. Similarly, adjusting the height of countertops is a separate process concerned with leveling surfaces rather than the specific structural elements in a drawer construction. Thus, the correct understanding of a sub-front emphasizes its position and importance in the drawer's assembly and performance.