The ridge board serves as the nailing surface for which of the following?

The ridge board functions primarily as a horizontal structural element located at the peak of a roof. It provides an essential nailing surface for the rafters, which are the sloped structural members that extend from the ridge board down to the walls of the building. When rafters are installed, they are typically secured to the ridge board to create a stable framework that supports the roof structure. This connection ensures that the weight of the roofing materials and any additional loads are properly distributed along the rafters to the walls below, contributing to the overall stability of the roof assembly.

In contrast, the other choices—ceiling, joists, and sheathing—do not interact directly with the ridge board in the same way rafters do. The ceiling is generally attached to horizontal framing members like ceiling joists, while joists are generally found in floors or ceilings rather than at the roof's apex. Sheathing is applied to the exterior of rafters rather than being directly associated with the ridge board. Thus, the key role of the ridge board as a nailing surface is specifically for the rafters.