Which horizontal structural member is located on top of the studs to hold the wall together?

The top plate is the horizontal structural member located at the top of the wall studs in a framing system. Its primary function is to provide structural support, tying the wall studs together and distributing loads effectively. This member plays a critical role in the overall integrity of the wall, allowing it to resist bending and lateral forces.

In typical wall framing, the top plate also serves as a connection point for the ceiling or roof framing, further enhancing stability and strength. It is crucial in ensuring that the walls maintain their shape and do not buckle under pressure, making it an essential component in both residential and commercial construction.

Other members mentioned serve different purposes; for instance, a base plate sits at the bottom of the studs and anchors the wall to the floor, while a rim board is typically used in floor framing to support the ends of the floor joists. Joists are the horizontal members that span an open space, usually beneath floors or ceilings, and do not directly hold the wall structure together as the top plate does. Hence, the top plate is the correct choice for this question.